diff --git a/docs/example_page_numbers_landscape.pdf b/docs/example_page_numbers_landscape.pdf
new file mode 100644
index 0000000..51cf4ce
Binary files /dev/null and b/docs/example_page_numbers_landscape.pdf differ
diff --git a/docs/example_page_numbers_landscape.tex b/docs/example_page_numbers_landscape.tex
new file mode 100644
index 0000000..2df5cc5
--- /dev/null
+++ b/docs/example_page_numbers_landscape.tex
@@ -0,0 +1,30 @@
+\documentclass[showtrims]{memoir}
+
+\usepackage{pgffor}  
+\usepackage[margin=0in]{geometry}
+
+\setstocksize{4cm}{6cm} 
+\settrimmedsize{4cm}{6cm}{*}
+%\addtolength{\textwidth}{8cm}
+%\addtolength{\textheight}{8cm}
+
+\setbinding{0cm} 
+\setlrmarginsandblock{0cm}{0cm}{*} 
+\setulmarginsandblock{0cm}{0cm}{*}
+
+\begin{document}
+
+\pagenumbering{gobble}
+
+\begin{center}
+
+\HUGE
+
+\foreach \n in {1,...,120}{
+	\vspace*{1cm} \underline{\n} \newpage
+}
+
+\end{center}
+
+
+\end{document}
\ No newline at end of file
diff --git a/docs/examples/octavo_wideSrc_90cwSrcRotation_letter.png b/docs/examples/octavo_wideSrc_90cwSrcRotation_letter.png
new file mode 100644
index 0000000..0dd5b07
Binary files /dev/null and b/docs/examples/octavo_wideSrc_90cwSrcRotation_letter.png differ
diff --git a/docs/examples/octavo_wideSrc_90cwSrcRotation_letter_paperRotated.png b/docs/examples/octavo_wideSrc_90cwSrcRotation_letter_paperRotated.png
new file mode 100644
index 0000000..0a3d58a
Binary files /dev/null and b/docs/examples/octavo_wideSrc_90cwSrcRotation_letter_paperRotated.png differ
diff --git a/docs/examples/octavo_wideSrc_noSrcRotation_letter.png b/docs/examples/octavo_wideSrc_noSrcRotation_letter.png
new file mode 100644
index 0000000..2b1507d
Binary files /dev/null and b/docs/examples/octavo_wideSrc_noSrcRotation_letter.png differ
diff --git a/docs/examples/octavo_wideSrc_noSrcRotation_letter_paperRotated.png b/docs/examples/octavo_wideSrc_noSrcRotation_letter_paperRotated.png
new file mode 100644
index 0000000..0e5ffae
Binary files /dev/null and b/docs/examples/octavo_wideSrc_noSrcRotation_letter_paperRotated.png differ
diff --git a/img/90ccwDiagram.png b/img/90ccwDiagram.png
new file mode 100644
index 0000000..595a099
Binary files /dev/null and b/img/90ccwDiagram.png differ
diff --git a/img/90cwDiagram.png b/img/90cwDiagram.png
new file mode 100644
index 0000000..70d421e
Binary files /dev/null and b/img/90cwDiagram.png differ
diff --git a/img/bottomBindingDiagram.png b/img/bottomBindingDiagram.png
new file mode 100644
index 0000000..b4adb41
Binary files /dev/null and b/img/bottomBindingDiagram.png differ
diff --git a/img/noRotationDiagram.png b/img/noRotationDiagram.png
new file mode 100644
index 0000000..b0c5db2
Binary files /dev/null and b/img/noRotationDiagram.png differ
diff --git a/img/topBindingDiagram.png b/img/topBindingDiagram.png
new file mode 100644
index 0000000..1134f13
Binary files /dev/null and b/img/topBindingDiagram.png differ
diff --git a/index.html b/index.html
index 5ccf613..10b0f28 100644
--- a/index.html
+++ b/index.html
@@ -28,6 +28,41 @@ <h2>File Info</h2>
                 <span class="row" style="padding: 10px;font-style: italic;">While some PDF viewers may display the first two pages as a spread, be aware that the first page, which is odd, will be on the right when printed. The first printed spread are pages 2 & 3 of your PDF document. Evens always on the left, odds always on the right.</span>
             </div>
 
+            <div class="section" id="input">
+                <h2>Source Manipulation</h2>
+
+                <span class="row"><input type="radio" id="none" name="source_rotation" value="none" checked>
+                    <label for="none">no modification</label>
+                    <details style="padding-left:40px;"><summary> Details</summary><IMG SRC="img/noRotationDiagram.png" width="100px"/></details>
+                </span>
+                <span class="row"><input type="radio" id="90cw" name="source_rotation" value="90cw">
+                    <label for="90cw">rotate all pages 90° clockwise</label>
+                    <details style="padding-left:40px;"><summary> Details</summary><IMG SRC="img/90cwDiagram.png" width="100px"/></details>
+                </span>
+
+                <span class="row"><input type="radio" id="90ccw" name="source_rotation" value="90ccw">
+                    <label for="90ccw">rotate all pages 90° counter clockwise (anti clockwise)</label>
+                    <details style="padding-left:40px;"><summary> Details</summary><IMG SRC="img/90ccwDiagram.png" width="100px"/></details>
+                </span>
+                <span class="row"><input type="radio" id="out_binding" name="source_rotation" value="out_binding">
+                    <label for="out_binding">Out binding </label>
+                       <details style="padding-left:40px;">
+                     <summary> Details</summary> 
+                     For books with the bound edge at the bottom of the page -- rotate all odd pages 90° clockwise, all even pages 90° anti-clockwise
+                     <BR/>
+                     <IMG SRC="img/bottomBindingDiagram.png" width="100px"/>
+                    </details>
+                </span>
+                <span class="row"><input type="radio" id="in_binding" name="source_rotation" value="in_binding">
+                    <label for="in_binding">In Binding</label>
+                        <details style="padding-left:40px;">
+                     <summary> Details</summary> 
+                     For books with the bound edge at the top of the page -- rotate all odd pages 90° anti-clockwise, all even pages 90° clockwise <BR>
+                     <IMG SRC="img/topBindingDiagram.png" width="100px">
+                     </details>
+                 </span>
+            </div>
+
             <!-- <div class="section" id="units">
                 <h2>Units</h2>
                 <span class="row"><input type="radio" id="inch" name="units" value="inch">
@@ -65,6 +100,11 @@ <h2>Printer</h2>
                     <span data-balloon-length="medium" aria-label="Duplex will alternate front and backs of sheets in a single file; Single-sided will split fronts and backs into seperate files." data-balloon-pos="up">ℹ️</span>
                 </span>
 
+                <span class="row">
+                    <label for="paper_rotation_90">Rotate Paper 90° <input type="checkbox" name="paper_rotation_90"></label>
+                    <span data-balloon-length="medium" aria-label="This puts your paper in 'landscape' -- layout still happens the same, but the porportions of things will be different" data-balloon-pos="up">ℹ️</span>
+                </span>
+
                 <span class="row"> <label>Alternate Page Rotation (AKA Flip on Long Side)<input type="checkbox" name="rotate_page"></label> <span id="folio_warning"><b>NOTE:</b> Not currently working for folios, sorry! Use the <a href="old/">old version</a> for now.</a></span></span>
                 
 
@@ -275,7 +315,6 @@ <h2>Signature Info</h2>
                 <center>
                     <iframe id="pdf" style="width: 100%; height: 10px;display:none;"></iframe>
                 </center>
-
                 <span class="row">Total Pages: <span id="total_pages"></span></span>
                 <span class="row">Total Sheets: <span id="total_sheets"></span></span>
                 <span class="row">Number of Signatures: <span id="sig_count"></span></span>
diff --git a/preload.js b/preload.js
index 01f9088..2a0a3a7 100644
--- a/preload.js
+++ b/preload.js
@@ -37,19 +37,23 @@ class Book {
         this.duplex = false; //FIXME
         this.duplexrotate = true;
         this.papersize = _constants_js__WEBPACK_IMPORTED_MODULE_6__.PAGE_SIZES.A4;   //  default for europe
+        this.paper_rotation_90 = false; // make the printed page landscape [for landscaped layouts, results in portait]
+
+        // valid rotation options: [none, 90cw, 90ccw, out_binding, in_binding]
+        this.source_rotation = 'none'; // new feature to rotate pages on the sheets 2023/3/09
+        this.managedDoc = null; // original PDF with the pages rotated per source_rotation - use THIS for laying out pages
 
         this.page_scaling = 'lockratio';
         this.page_positioning = 'centered';
         this.flyleaf = false;
         this.spineoffset = false;
         this.format = 'standardsig';
-        this.booksize = [null, null];
         this.sigsize = 4;       //  preferred signature size
         this.customsig = null;
         this.signatureconfig = [];  //  signature configuration
 
         this.input = null;    //  opened pdf file
-        this.currentdoc = null;    //  Itext PDFReader object
+        this.currentdoc = null;    //  uploaded PDF [Itext PDFReader object] untouched by source_rotation - use managedDoc for layout
         this.pagecount = null;
         this.cropbox = null;
 
@@ -71,7 +75,14 @@ class Book {
 
         this.duplex = form.get('printer_type') == 'duplex';
         this.duplexrotate = form.has('rotate_page');
+        this.paper_rotation_90 = form.has('paper_rotation_90');
         this.papersize = _constants_js__WEBPACK_IMPORTED_MODULE_6__.PAGE_SIZES[form.get('paper_size')];
+        if (this.paper_rotation_90) {
+            this.papersize = [this.papersize[1], this.papersize[0]]
+        }
+
+        this.source_rotation = form.get("source_rotation");
+        
         this.page_scaling = form.get("page_scaling");
         this.page_positioning = form.get("page_positioning");
         this.flyleaf = form.has('flyleaf');
@@ -92,10 +103,8 @@ class Book {
                     this.signatureconfig.push(num);
                 }
             });
-
         }
 
-        this.booksize = [this.papersize[1] * 0.5, this.papersize[0]];
         this.page_layout = form.get('pagelayout') == null ? 'folio' : _constants_js__WEBPACK_IMPORTED_MODULE_6__.PAGE_LAYOUTS[form.get('pagelayout')];
         this.per_sheet = this.page_layout.per_sheet;
         this.pack_pages = form.get('wacky_spacing') == 'wacky_pack';
@@ -148,19 +157,8 @@ class Book {
 
     }
 
-    setbooksize(targetsize, customx, customy) {
-        if (targetsize == 'full') {
-            this.booksize = [this.papersize[1] * 0.5, this.papersize[0]]
-        } else if (targetsize == 'custom') {
-            this.booksize = [customx, customy];
-        } else {
-            this.booksize = _constants_js__WEBPACK_IMPORTED_MODULE_6__.TARGET_BOOK_SIZE[targetsize];
-        }
-
-    }
-
     createpagelist() {
-        this.pagecount = this.currentdoc.getPageCount();
+        this.pagecount = (this.managedDoc == null) ? this.currentdoc.getPageCount() : this.managedDoc.getPageCount();
         this.orderedpages = Array.from({ length: this.pagecount }, (x, i) => i);
 
         if (this.flyleaf) {
@@ -188,8 +186,42 @@ class Book {
         console.log("Calculated pagecount [",this.pagecount,"] and ordered pages: ", this.orderedpages)
     }
 
-    createpages() {
+    async createpages() {
         this.createpagelist();
+        this.managedDoc = await pdf_lib__WEBPACK_IMPORTED_MODULE_0__.PDFDocument.create()
+        var pages = this.currentdoc.getPages();
+        for (var i = 0; i < pages.length; ++i) {
+            var page = pages[i]
+            var embeddedPage = null
+            var newPage = this.managedDoc.addPage();
+            var rotate90cw = this.source_rotation == '90cw' 
+                || (this.source_rotation == 'out_binding' && i % 2 == 0)
+                || (this.source_rotation == 'in_binding' && i % 2 == 1)
+            var rotate90ccw = this.source_rotation == '90ccw' 
+                || (this.source_rotation == 'out_binding' && i % 2 == 1)
+                || (this.source_rotation == 'in_binding' && i % 2 == 0)
+
+            if (this.source_rotation == 'none') {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [1, 0, 0, 1, 0, 0]);
+                newPage.setSize(embeddedPage.width, embeddedPage.height);
+            } else if (rotate90ccw) {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [0, 1, -1, 0, page.getHeight(), 0]); // this is CCW
+                newPage.setSize(embeddedPage.height, embeddedPage.width);
+            } else if (rotate90cw) {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [0, -1, 1, 0, 0, page.getWidth()]); // this is CW
+                newPage.setSize(embeddedPage.height, embeddedPage.width);
+            } else {
+                var e = new Error("??? what sorta' layout you think you're going to get?");
+                console.error(e);
+                throw e;
+            }
+            newPage.drawPage(embeddedPage);
+            embeddedPage.embed();
+            this.cropbox = newPage.getCropBox();
+        }
+
+        console.log("The updatedDoc doc has : ", this.managedDoc.getPages(), " vs --- ", this.managedDoc.getPageCount());
+        
         if (this.format == 'booklet') {
             this.book = new _booklet_js__WEBPACK_IMPORTED_MODULE_3__.Booklet(this.orderedpages, this.duplex);
         } else if (this.format == 'perfect') {
@@ -222,7 +254,8 @@ class Book {
         //  create a directory named after the input pdf and fill it with
         //  the signatures
         this.zip = new (jszip__WEBPACK_IMPORTED_MODULE_8___default())();
-        this.filename = this.inputpdf.replace(/\s|,|\.pdf/, '');
+        var origFileName = this.inputpdf.replace(/\s|,|\.pdf/, '');
+        this.filename = origFileName
 
         if (this.format == 'booklet') {
             await this.createsignatures(this.rearrangedpages, 'booklet');
@@ -241,14 +274,18 @@ class Book {
                 }
             }
             await forLoop();
+
             if (this.duplex && this.rearrangedpages.length > 1) {
                 await aggregatePdf.save().then(pdfBytes => { 
+                // await this.managedDoc.save().then(pdfBytes => { 
                     if (!isPreview) 
                         this.zip.file('aggregate_book.pdf', pdfBytes); 
                 });
             }
+            var rotationMetaInfo = ((this.paper_rotation_90) ? "_paperRotated" : "")
+                + ((this.source_rotation == 'none') ? "" : `_${this.source_rotation}`)
+            this.filename = `${origFileName}${rotationMetaInfo}`
             resultPDF = aggregatePdf;
-            // // SHARKS
         } else if (this.format == 'a9_3_3_4') {
             resultPDF = await this.buildSheets(this.filename, this.book.a9_3_3_4_builder());
         } else if (this.format == 'a10_6_10s') {
@@ -305,7 +342,7 @@ class Book {
             }
         });
 
-        let embeddedPages = await outPDF.embedPdf(this.currentdoc, filteredList);
+        let embeddedPages = await outPDF.embedPdf(this.managedDoc, filteredList);
         blankIndices.forEach(i => embeddedPages.splice(i, 0, 'b'));
 
         let block_start = 0;
@@ -701,7 +738,7 @@ class Book {
             console.warn("All the pages are empty! : ",pagelist);
             return;
         }
-        let embeddedPages = await outPDF.embedPdf(this.currentdoc, filteredList);
+        let embeddedPages = await outPDF.embedPdf(this.managedDoc, filteredList);
         // TODO : make sure the max dimen is correct here...
         let papersize = isLandscape ? [this.papersize[1], this.papersize[0]] : [this.papersize[0], this.papersize[1]]
         let curPage = outPDF.addPage(papersize);
@@ -31379,6 +31416,9 @@ function renderInfoBox(book) {
     const sigArrange = document.getElementById('sig_arrange');
     const totalPages = document.getElementById('total_pages');
 
+    if (book.book == null || book.book == undefined)
+        return
+
     const outputPages = book.book.pagelist.reduce((acc, list) => {
         list.forEach((sublist) => (acc += sublist.length));
         return acc;
diff --git a/src/book.js b/src/book.js
index 88f4ba3..589894a 100644
--- a/src/book.js
+++ b/src/book.js
@@ -1,4 +1,4 @@
-import { PDFDocument, degrees, rgb } from 'pdf-lib';
+import { PDFDocument, degrees, grayscale, rgb } from 'pdf-lib';
 import { saveAs } from 'file-saver';
 import { Signatures } from './signatures.js';
 import { Booklet } from './booklet.js';
@@ -15,19 +15,23 @@ export class Book {
         this.duplex = false; //FIXME
         this.duplexrotate = true;
         this.papersize = PAGE_SIZES.A4;   //  default for europe
+        this.paper_rotation_90 = false; // make the printed page landscape [for landscaped layouts, results in portait]
+
+        // valid rotation options: [none, 90cw, 90ccw, out_binding, in_binding]
+        this.source_rotation = 'none'; // new feature to rotate pages on the sheets 2023/3/09
+        this.managedDoc = null; // original PDF with the pages rotated per source_rotation - use THIS for laying out pages
 
         this.page_scaling = 'lockratio';
         this.page_positioning = 'centered';
         this.flyleaf = false;
         this.spineoffset = false;
         this.format = 'standardsig';
-        this.booksize = [null, null];
         this.sigsize = 4;       //  preferred signature size
         this.customsig = null;
         this.signatureconfig = [];  //  signature configuration
 
         this.input = null;    //  opened pdf file
-        this.currentdoc = null;    //  Itext PDFReader object
+        this.currentdoc = null;    //  uploaded PDF [Itext PDFReader object] untouched by source_rotation - use managedDoc for layout
         this.pagecount = null;
         this.cropbox = null;
 
@@ -49,7 +53,14 @@ export class Book {
 
         this.duplex = form.get('printer_type') == 'duplex';
         this.duplexrotate = form.has('rotate_page');
+        this.paper_rotation_90 = form.has('paper_rotation_90');
         this.papersize = PAGE_SIZES[form.get('paper_size')];
+        if (this.paper_rotation_90) {
+            this.papersize = [this.papersize[1], this.papersize[0]]
+        }
+
+        this.source_rotation = form.get("source_rotation");
+        
         this.page_scaling = form.get("page_scaling");
         this.page_positioning = form.get("page_positioning");
         this.flyleaf = form.has('flyleaf');
@@ -70,10 +81,8 @@ export class Book {
                     this.signatureconfig.push(num);
                 }
             });
-
         }
 
-        this.booksize = [this.papersize[1] * 0.5, this.papersize[0]];
         this.page_layout = form.get('pagelayout') == null ? 'folio' : PAGE_LAYOUTS[form.get('pagelayout')];
         this.per_sheet = this.page_layout.per_sheet;
         this.pack_pages = form.get('wacky_spacing') == 'wacky_pack';
@@ -126,19 +135,8 @@ export class Book {
 
     }
 
-    setbooksize(targetsize, customx, customy) {
-        if (targetsize == 'full') {
-            this.booksize = [this.papersize[1] * 0.5, this.papersize[0]]
-        } else if (targetsize == 'custom') {
-            this.booksize = [customx, customy];
-        } else {
-            this.booksize = TARGET_BOOK_SIZE[targetsize];
-        }
-
-    }
-
     createpagelist() {
-        this.pagecount = this.currentdoc.getPageCount();
+        this.pagecount = (this.managedDoc == null) ? this.currentdoc.getPageCount() : this.managedDoc.getPageCount();
         this.orderedpages = Array.from({ length: this.pagecount }, (x, i) => i);
 
         if (this.flyleaf) {
@@ -166,8 +164,42 @@ export class Book {
         console.log("Calculated pagecount [",this.pagecount,"] and ordered pages: ", this.orderedpages)
     }
 
-    createpages() {
+    async createpages() {
         this.createpagelist();
+        this.managedDoc = await PDFDocument.create()
+        var pages = this.currentdoc.getPages();
+        for (var i = 0; i < pages.length; ++i) {
+            var page = pages[i]
+            var embeddedPage = null
+            var newPage = this.managedDoc.addPage();
+            var rotate90cw = this.source_rotation == '90cw' 
+                || (this.source_rotation == 'out_binding' && i % 2 == 0)
+                || (this.source_rotation == 'in_binding' && i % 2 == 1)
+            var rotate90ccw = this.source_rotation == '90ccw' 
+                || (this.source_rotation == 'out_binding' && i % 2 == 1)
+                || (this.source_rotation == 'in_binding' && i % 2 == 0)
+
+            if (this.source_rotation == 'none') {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [1, 0, 0, 1, 0, 0]);
+                newPage.setSize(embeddedPage.width, embeddedPage.height);
+            } else if (rotate90ccw) {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [0, 1, -1, 0, page.getHeight(), 0]); // this is CCW
+                newPage.setSize(embeddedPage.height, embeddedPage.width);
+            } else if (rotate90cw) {
+                embeddedPage = await this.managedDoc.embedPage(page, undefined, [0, -1, 1, 0, 0, page.getWidth()]); // this is CW
+                newPage.setSize(embeddedPage.height, embeddedPage.width);
+            } else {
+                var e = new Error("??? what sorta' layout you think you're going to get?");
+                console.error(e);
+                throw e;
+            }
+            newPage.drawPage(embeddedPage);
+            embeddedPage.embed();
+            this.cropbox = newPage.getCropBox();
+        }
+
+        console.log("The updatedDoc doc has : ", this.managedDoc.getPages(), " vs --- ", this.managedDoc.getPageCount());
+        
         if (this.format == 'booklet') {
             this.book = new Booklet(this.orderedpages, this.duplex);
         } else if (this.format == 'perfect') {
@@ -200,7 +232,8 @@ export class Book {
         //  create a directory named after the input pdf and fill it with
         //  the signatures
         this.zip = new JSZip();
-        this.filename = this.inputpdf.replace(/\s|,|\.pdf/, '');
+        var origFileName = this.inputpdf.replace(/\s|,|\.pdf/, '');
+        this.filename = origFileName
 
         if (this.format == 'booklet') {
             await this.createsignatures(this.rearrangedpages, 'booklet');
@@ -219,14 +252,18 @@ export class Book {
                 }
             }
             await forLoop();
+
             if (this.duplex && this.rearrangedpages.length > 1) {
                 await aggregatePdf.save().then(pdfBytes => { 
+                // await this.managedDoc.save().then(pdfBytes => { 
                     if (!isPreview) 
                         this.zip.file('aggregate_book.pdf', pdfBytes); 
                 });
             }
+            var rotationMetaInfo = ((this.paper_rotation_90) ? "_paperRotated" : "")
+                + ((this.source_rotation == 'none') ? "" : `_${this.source_rotation}`)
+            this.filename = `${origFileName}${rotationMetaInfo}`
             resultPDF = aggregatePdf;
-            // // SHARKS
         } else if (this.format == 'a9_3_3_4') {
             resultPDF = await this.buildSheets(this.filename, this.book.a9_3_3_4_builder());
         } else if (this.format == 'a10_6_10s') {
@@ -283,7 +320,7 @@ export class Book {
             }
         });
 
-        let embeddedPages = await outPDF.embedPdf(this.currentdoc, filteredList);
+        let embeddedPages = await outPDF.embedPdf(this.managedDoc, filteredList);
         blankIndices.forEach(i => embeddedPages.splice(i, 0, 'b'));
 
         let block_start = 0;
@@ -679,7 +716,7 @@ export class Book {
             console.warn("All the pages are empty! : ",pagelist);
             return;
         }
-        let embeddedPages = await outPDF.embedPdf(this.currentdoc, filteredList);
+        let embeddedPages = await outPDF.embedPdf(this.managedDoc, filteredList);
         // TODO : make sure the max dimen is correct here...
         let papersize = isLandscape ? [this.papersize[1], this.papersize[0]] : [this.papersize[0], this.papersize[1]]
         let curPage = outPDF.addPage(papersize);
diff --git a/src/book.test.js b/src/book.test.js
index 199d9a4..c9e52dd 100644
--- a/src/book.test.js
+++ b/src/book.test.js
@@ -12,7 +12,6 @@ describe('Book model', () => {
         flyleaf: false,
         spineoffset: false,
         format: 'standardsig',
-        booksize: [null, null],
         sigsize: 4,
         customsig: null,
         signatureconfig: [],
diff --git a/src/utils/renderUtils.js b/src/utils/renderUtils.js
index 17f7bdd..f39bcd3 100644
--- a/src/utils/renderUtils.js
+++ b/src/utils/renderUtils.js
@@ -11,6 +11,9 @@ export function renderInfoBox(book) {
     const sigArrange = document.getElementById('sig_arrange');
     const totalPages = document.getElementById('total_pages');
 
+    if (book.book == null || book.book == undefined)
+        return
+
     const outputPages = book.book.pagelist.reduce((acc, list) => {
         list.forEach((sublist) => (acc += sublist.length));
         return acc;