2024-12

inputs/2024/12.txt

@@ -0,0 +1,140 @@
+OBBBBLLLLLLVVVVVVVVVVVVVVMMMMMMMMMMMMMMMMMMMMMJJJJJJJJJJOOOOOOORRRRRRRRRRRRRRRRRRRRXXXXXXXXXXXXXXXUUUUXBXXAXXDDDDDDNNNNNNNNNNNNNNNNTTTLHHLLL
+OBBBBBLLLLLLVVVVVVVVVVVVVVVVSSMMVVVMVVMMMMMMMMLJJJJJJJJJOOOORRRRRRRRRRRRRRRRRRRRRRRXXXXXXXXXXXXXXXUUXUXBXXXXXDDDDDDNNNNNNNNNNNNNNONTLLLLLLLL
+OBBBBBLLLLKKKKKVVVVVVVVVVFVSSSSMMMVVVVVMMMMMMMLLJJJJJJJJJOOOOORRRRRRRRRRRRRRRRRRRRDDDXXXXXXXXXXXJXXXXXXXXXXXXDDDDDDDNNNNNNNNNNNNNNNTLLLLLLLL
+OJXXXJJLLLLKKVVVVVVVVVVVVFVSSSSSMVVVVVVMMMMMMMLLJJJJJJJJOOOOOQQRRRRRRRRRRRRRRRRRRRDDPPXXXXXXXXXXJXXXXXXXXXXXXXXXDDDDDNNNNNNNNNNNNNTTLLLLLLLL
+OJXXXJJJLLKKWVVVVVVVVVVFFFSSSSSMMVZVVVVVMMMMMLLLJJJJJGGGOOOOQQQRWRRRRRRRRRRRRRRRRRRRPYXXXXXXXXXXJXXXXXXXXXXXXXXXDDDDDNNNNNNNNNNNNLLLLLLLLLLL
+JJXXJJJJJJJJVVVVVVGGGFFFFFSSSSSSMMVVRWWLLMMMLLLLJJJJJJGGOGOQQQQQWRRRRRRRRRRRRIRPRRPPPPPPXXXXXXXXJXMXXXXXXXXXXXXXDDDDNNNNNNNNNNNNNNEELLLLLLLL
+JJJJJJJJJJJJJJJVVGGGGFFFFFFFFSSSMMMMWWWWLLMMLLLLLLJJJGGGGGGQQQQQQRRRRRRRRRIRRIPPPPPPPPPPXXXXXXXXXXMMXXXXXXXXXXXXXXDDNNNNNNNNNNNNNNNELLLLLLLL
+JJJJJJJJJJJJZZZZGGGGGGGGGGGFSSSMMMMMWWWMWLLLLLLLLLJLGGGGGGGGQQQQQQQQRRRRIIIRIIPPPPPPPPPXXXXXXXCXXXMMHMXXXXXXLXXXDDDDDDNNNNFFNNMNJJLLLLLLLLLL
+JJJJJJJJZZZZZZZZXGGGGGGGGGGGTGSMMMMMWWWWWLLLLLLLLLLLLGGGGMGGQQQQQQQQRRRRIIIIIIPPPPPPPPPXVVVTTXCCXXMMMMXXXXXXLLXXDDDDDDDNDNNNDNNJJJJLLLLLLLLL
+JJJJJJJJJZZZZZZGGGGGGGGGGGGGGGGMMMMWWWWWWWWLLLLLLLLLLLGGGGGQQQQQQQQQQRRQGIUIIIIPPPPPPPPPVVVTXXXXXXMMMMXXXXLLLLLLDDDDDDDDDDDDDNNJJJJJJLLLLLLL
+JJJJJJJJJJZZZZZGGGGGGGGGGGGGGGGGMMWWWWWWWWWWLLLLLLLLLGGGGGGQQQQQQQQQQQQQQQUIIIKKPPPPPPPPVVVVVXXXXXXMMMXXXLLLLLLDDDTTDDTDDDDDDDDJJDJJJLLLLLLL
+JJJJJJJJJJZZZZZZGGGGGGGGGGGGGGGGMWWWWWWWWWWWWWLLLLLGGGGGGGGQQQQQQQQQQQQQQQIIKKKPPPPPPPPPPPVVPPPXXXXMMXXXXXLLLLLLTTTTTTTTTDDDDDDDDDJJJJZLLLLL
+JJJJJJJJJJZZZZZZGGGGGGGGGGGGGGGGWWWWWWWWWWWWWLLLLLLGGGGGGGGQQQQQQQQQQQQQQQIIKYYPPNLPPPPPPPPVPPPXXXXXXXXXXXLLLLLTTTTTTTTDDDDDDGDDZDJJJJJLUUUL
+JJJJJJJJJZZZZZZZZZGGGGGGGGGGGGGWWWWWWWWWWWWVVLLLLLLGGGGGGQQQQQQQQQQQQSQQYYIIIYLLPLLLLPPPPPPPPXXXXXXXXXXXXXXLTTTTTTTTTTHDDHDDDGDDDCCJJJJJUUUU
+JJJJJJJJZZZZZZZZZZZGGGGGDGGGFFWWWWWWWWWWWWWVVVLLLLLGGGGGGQQQQQQQQQQQSSQYYYYIYYYLLLLLLLPPPPPPPXXXXXXXXBBXXRXTTTTTTTTTTTHHHHHHYHHRRCCJJJJJJUUU
+ZJJJJJJJJZZZZZZZZZGGGGGGGUUUFFFFFWWWWWWWWWWVVVLLLLLLLLGGIQQQQQQQQQQSSYQYYYYYYYYLLLLLLLPPPPPPXXXXXXXXXXTTXTTTTTTTTTTTTIHHHHHHHHRHCCCCEJJJUUUU
+ZJJJJJJJJZZZZMMZZZZGAAGGFFFUFFFFFWWWWWFFVQWVVVVVVLLLLLGGGQQQQQQQQQQQQYQYYYYYYYYYYLLLLLLLPPXXXXXWXXXXXTTTTTTTTTTTTTTTTILHHHHHHHHHEDDEEJJJUUUU
+ZZZZZJJJZZZMMMMZZZZZAAGAFFFFFFFFWWWWWWWWVVVVVVVVLLLLLGGGGAAAAQQQQQQYYYYYYYYYYYYYYYLLLLLLXXXXXXXXXXSXQQTTTTTTTTTTTTTTIIIIHHHHHHHHHDDDDDUUUUUU
+ZZZZZZZZZZMMMMMZZZZZAAAAFFFFFFFFFWWWWWWVVVVVVVVAALAAAGJJJAAAAAQQQQYYYYYYYYYYYYYYYYLLLLWLXXXXXXXXXXXXTTTTTTTTTTTITTITIIIDHHHHHHHHPDDDDDUUUUUU
+ZZZZZZZZZMMMMMMMZMZMAAAAAFFFFFFWWWWWWWWVVVVVVVAAAAAAAGJJJJAAAADDDYYYYYYYYYYYYBBBYYLLLLWWWWXXXXXXXXXBTTTTTTTTTTTITIIIIIIDDDHHHHHDDDDDDUUUUUUU
+ZZZZZZZZMMMMMMMMMMMMAAAAAAAAAAFFDWWWWSSVVVVVAAAAAAAAAAAJJJAAAAADDYYYYWYYSYYYYBBGYYYDDXXXXWXXXXXXXXXBBBTTTTTTTTIIIIIIIIIIDDDDHHHDDDDDDUUUUUUU
+ZZZZZZZZZMMMMMMMMAAAAJEEEEAAAAAFDDWWLLLBBBBVAAAAAAAAAAAJJJAAAAYYYYWZWWWYSYYSYBBYYSDDDXXXXXXXXXXXXXXBBBTTTTTTTIIIIIIIIIIIDDDDDHHDDDDDUUUUUUUU
+ZZIIZZZMMMMMMMMMMAAAAAEEEEEAAAAALLLLLLLLLVVVOAAAAAAAAAAJJJJAAYYYYYWWWWWWSSSSSSSSSSDDXXXXXXXXXXXXXXXBBBBTTTTTGGGOIIIIIIIIDDDDDDDDDDDDUUUUUUUV
+IIIIZZZZZMMZMMMMMMMAABEEEEEAAAAAALLLLLLLLBVVVAAAAAAAAAJJJJJJYPPYYYWWUWWWSSSSSSSSSSDDDDXXXXXXXXXXXXXXBBBTBBTTGGGGIIIIIIIIDDDDDDDVVIVVVVUUUVVV
+GGIIIIZZZZZZMMMMMMYAEEEEEEEEAAMMMLQLLLLLLBBVGGGAAAAAAAGGJJJJYYYYYYYYUWZWSSSSSSSSDDDDDDXXXXXXXNNXXXXBBCBBBBBTGGGCIIIIIIIIDDDDDDVVVVVVVUUUUVVV
+IIIIIIIIZZMMMMMMMMYYEEEEEEJEAAMMMQQQLLLLLLBGGGGGAAASAAGGJJJJYYYYYYYWWWWSSSSSSSSDDDDDDDXXXXXXXNXXXXXBBCBBCBBCCGCCCICIIIIDDDDDDDVVVVVVVVUUUVVV
+IIIIIIIIIIMMMMMMMMMYYEEEJJJJAMMMMMMLLLLLDBBBBBBGGGAAAAGGJJYYYYYYYYYYWKWSSSSSSSSSDDDDDWWWWWWXNNXXNXXBCCCCCCBCCCCCCCCIDDDDDDDDDVVVVVVVVVVVVVVV
+IIIIIIIIIIMMMMMMMMYYYYYEJJJJAMMMMMMMMMBLBRBBBBGGGGGGGGGGJJJYYYYYYYYYSSSSSSSSSSSSSSDDWWWTWWWNNNNNNWCCCCCCTCCCCCQCCCCDDDDDDDDDDDVVVVVVVVVVVVVN
+IIIIIIIIIIQMMMMMMMYYYYYEMMMMMMMMMMMMMBBBBBBBBBBGGGGGGGGGGJJJYYYYYYYSSSSSSSSSSSSSSSSSWWWWWWWNWNNNCCCCCCCCTCCCCCQCCCCDDDDDDDDDDDDDVVVVVVVVJVVV
+IIIIIIIIIIIIMMMMMMYYYYYYYYYYMMMMMMMBMBBBBBBBBBBGGGGGGGGGGYJYYYYYYYYYSSSTSSSSSSSSKWWWWWWWWWWWWNNNNNCCCCCCCCCCCCCCCCDDDDDDDDDDDDDDVVVVVVVVVVVV
+IIIIIIIIIIIIIMMMMZYYYYYYYYYYMMMMMMMBBBBBBBBBBBBGGGGGGGGGYYYYYYYYYYYYYSSTSSSSSSHSKWWWWWWWWWWWWNNNNNCCCCCCCCCCCCCCCCBDDDDDDDDDDDVVVVVVVVVVVVVV
+IIIIIIIIIIIIMMMIZZZZYYYYYYYYYMMMMNBBBBBBBBBBBBGGGGGGGQQQGGYYYYYYYYYYYYYYYSSSSSSSWWWWWWWWWWWWWWNNNNCCCCCCCCCCCCCCCCBDDDDDDLDLDDVVVVVVVVVVVVVV
+IIIIIIIIIIIMMZZZZZZZYYYYYYYYYYMNNNNBBBBBBBBBBBBBBGGGGQQQYYYYYLLYYYYYYYYSSSSSSSSSSWWWWWWWWWWWWWNNNNNNCCCCCCCCCCCCCCCCRRRDDLQLLDVVVVVVVVVVVVVV
+IIIIIIIIIOIOMRZZZZZZYYYYYYYYYYMMNBBBBBBBBBBBBBBBGGGGGQQQYYFYBLLYYYYYYYYSNSSSSSSSSWBBHWWWWWWWSSNCNNCCCCCCCCCCCCCCCYYYRRRRLLLLLDLQVLVVVVVVVVVV
+IIIIIIIOOOOOMZZZZZZZYYYYYYJJYYMMBBBBBBBBBBBBBQQBGGGQQQQQFFFBBLLLYYYLYYYSNNSBBBZSSSBBWWWHWWWWWWNCNCCCCCCUCCCCCCCCYYUYRRRRLLLLLLLLLLVVVVVVZVVV
+IIIIIOIOOOOOOZZZZZZYYYYYYJJJJYYIMBBBBBBBBBBBBBQQGGGQQQQQTWBBBLLLYYYLYYYYNBBBBBBBSBBBDWWWWWWWWWCCNCCCCCCUCCCCUUUUUUUURRRLLLLLLLLLLLLVVVZVZVVV
+IIIOOOOOOOOOZZZZZZZZZZYYYJJJYYYIIIIBBBBBBBBBBBQQQGGQQQQQWWBBBBLLYYYLLNNNNNNBBBBBBBBBDDWWWIIWWWCCCCCMMMMMCCCUUUUUUUUURRLLLLLLLLLLLLLVZZZHHYYY
+IIIIOOOOOOOOZZZZZZZZZZYYYYYYYYITIIIIBBBBBBBBBBQQQGGQQQQQWWLBLLLLLLLLLLNNNNBBBBBBBBBBBDDDIIIWWWCCCCCMMMMMCCCUUUUUUUUURRLLLLLLLLLLLLLLLZZHHHYH
+IIIIOOOOOOOOOZZZZZZZZZYYYYYYYIIIIIIIIBBBBBBBDDQQGGGQQQWWWWLLLLLLLLLLLLNNNNBBBBBBBBBBBDDDIIWWCCCCCMMMMMMMUCUUUUUUUUUIRRLLPPLLLLLLLLLLLLZHCHYH
+IIIIIOOOOOOOZZZZZZZZZZYYYYIIIIIBIIIIIBBBBMCBDDDDGGGQQQWWWWLLLLLLLLLLLLLNNBBBBBBBBBBBKBBDFFWWWCCCCMMMMMMMMUUUUIUUUUUIIRLPPPPLLLLLLLLLLLHHHHHH
+IIIIIOIIOOOOZZZZZZZZZYYYYYYYIIBBIIIIIBMMMMCCDDDDDDGGWWWWWWLLLLLLLLLLLLLLNBBBBBBBBBBBBBVDQFFCCCCCCMMMMMMMIIUIUUUUUIIIIIPPPPPPLLLLLLLLLLHHHHHH
+IIIIIIIIIOOOFZZZZZZZZZYYYYYYBBBBBBBIIIIIICCCDDDDDDGDDDDWWWWWWLLLWWLLLGGGBBBBBBBBBBBBBBBAFFCCCCCCCMMMMMMMMIUIIUUIIIIIIQPPPPPLLLLLLLLLLLHHHHHH
+IIIIIIIXIIFFFZZZZZZZZZZYYYYYBBBBBBIIIITCCCCDDDZZDDDDDZZWWWWWWWWLLWWLLLGGIIIIIBBBBBBTBBFFFFCCCCCCCCMMMMMMMIIIIIIIIIIIIQQPPPPPLLLLLLLLLLHHHHHH
+IIIIIIIXIFFFFZZZZZZZZZZYYYBBBBBBBBIIIIICCPPDDZZZDDDDDZZWWWWWWWWWWWWLLGGGIIIIIBBBBOBTBFFFFFCCCCCCCCCCMMUMIIIIIIIIIIIIQQQQPPPLLLLLLHHHHHHHHHHH
+IIIIIIIXIFFFFFFZZZZZZZZBBBBBBBBBBBDICCCCCCPDPZZZDDDZZZZZWWWWWWWWWWWGGGGGIIIIIBBBBTTTTTFFFFCCRRCCCCCCCMVIIIIIIIIIIIIIIQQQPPQLQLLLLHHHHHHHHHHH
+IIIIIXXXIIFFFFFXXZZZZZZBBBBBBBBBBBBCCCCCCCPPPIZZZZZZZZZZZZZWWWWWWWWGGGKKIIIIIBBBTTTTTTFFTTTRRRCCCCCCZMVVIVIIIIIMMIIIIQQQQQQQQQQQLQHHHHHHHHHH
+IIXXXXXXFFFFFFFFFZZZZZBBWBBBBBBBBBBCCCCCCCCPPZZZZZZZZZZZZZZWWWWWWWWWKGKKIIIIIBBTTTTTTTFFTTRRRRRCCCCVVVVVVVIIIIIMMIIIIIQQQQQQQQQQQQQQHHHHHHHE
+IVXXXXXXXFFFFFFGFZZZZZBWWBBBKKBBBBNNCCCCCPPPPPPZRZZZZZZZZZWWWWWWWKKKKKKKIIIIITTTTTTTTTFFTTRRRRRCVVVVVVVVVVVIIGGMMMIIIIIIXXQQQQQQQQQHHHHHRRRE
+IVVXXXXXXAFFFFFFFFZZZZZZBBBKKKKBBNNCCCCCCCPPPPPPRZZZZZZZZWWWWWWWKKKKKKKKIIIIIGTTTTTTTTTTTTXRRGGGGVVVVVVVVVVVGGGMMMMMMMIIXXQQQQQQQQQHHHRHRRRE
+VVVVVXSTXTTFFFFZZZZZZZZBBKUUUUUKKCCCCCCCCPPPPPPPPZZZZZZZZWWWWWWWIIKKKKKKIIIIITTTTTTTTTTTTTXGGGGGGVVVVVVVVVVVGGGMMMMTMMXXXXQQQQQQQNNNHRRRRRRE
+VVVVVVVTTTTFFFSZZZZZZZZZKKUUUUUKKCCCCCPPCPPPPPPPPZZZFFFZPPWWWWWWIIKKKKKKIIIIITTTTTTTTTTXXXXXGGGGGVVVVVVVVVVVMMMMMMMMEEXXXXOXQQQNNNNNHWRRRRRR
+VVVVVVVVTTTTZFZZZZZZZZZZZZUUUUUKKKKCCCCPPPPPPPPPPZZZZFFZPPPWSWWWIKKKKKMKIIIIITTTTTTTTTXXXXXXXGGMMMMVVVVVVVVMMMMMMMMMEEXXXXXXXQQNNNNRRRRRRRRR
+VVVVVVVVVTTTZZZZZZZZZZZZZZUUUUUKKKKKCCCPPPPPPPPPPZZFFFCPPPSSSSSWIKKKKKKKNNTTTTTTTTTTTTXXXXXGGGGMMMMVVVVVVVMMMMMMMMMWMXXXXXXXXXNNNNNRRRRRRRRR
+VVVVVVVVVVTTZZZCCCZZZZZZZZUUUUUKKKKKOCCCPPPPPPPHPRZCCFCCSSSSSSSSIIIIIKKNNNNNNTTTTTTTTTXXXXGGGGMMBMMMMVVVVMMMMMMMMMMMMXXXXXXXXXXNNNRRRRRRRRRR
+VVVVVVVVVVTTTZUFCCFZZZZZZDUUUUUKKKKKOOOIPMPPPPPPPRRRCCCCSSSSSSSSSISSSNNNNNNNNTTTTTTTTTTXGGGGGGMMMMMMMVVKMDMMMMMMMMMMXXXXXXXXXXXNNNNNRRRRRRRR
+VVVVVVVVVTTTTZFFFFFWZZMMDDDDDDDDKKKOOOOOOMMPPPPPRRRCCCBCFSSSSSSSSSESSSNNNNNNNTTTTTTTTTTTAAGGGGMMMMMMMMMMMMMMMMMMMMMMGXXXXXXXXXXNNNNNRRRRRRRR
+VVVVVVVTTTTTTTTFFFFFFDDDDDDDDDDDKKOOOOOOOMPPPPPPCRRRCCCCCCSSSSSSSSSSSNNNNNNNNNNNTTTTTTTTAAGGGMMMMMMMMMMMMMBMMMMMMMMMXXXXXXXXXXNNNRRRRRRRRRRR
+VVVVVVVVVTTTTTTTFFFFFRDDDDDDDDDDKKOOOOOOMMMMPXXXCCCCCCCCCYSSSSSSSSSSSNNNNNNNNNNNNNNTTTTHHAGGGMMMMMMMMMMMMMMMMMMOOMMMOXXXXXXXXYXRRRRRRRRRRRRR
+VDDDVVVVVTTTTTTTTBBBBRBDDDDDDDDDKOOOOOOOOOWWWWXXXCCCCCCCCCSSSSSSSSSNNNNNNNNNNNNNYNNAAATHHAAGGMMMMMMMMMMMMMMMXXOOOOOOOOOXXXXXXXXXRRRRRRRRRRRR
+VDDDTTTTTTTTTTTTBBBBBBBBBDDDDKKKKKOOOOOOOZZWWWWWXXXCCCICSCSSSSSSSSSNNNNNNNNNNNYYYNNAAAAAAAAGGGMMMMMMHHMMMMXMXXOOOOOOOOXXXXXXXXXXSSRRRRRRRRRF
+DDDDDTTTTTBBTTTTBBBBBBBBBDBBBKKKKKOOOOOOOOZWWWWWXXXXXKIISSSSSSSSSSLSNNNNNNNNNNYYYNNAAAAAAAAGGGMMMXMMHHMMMMXXTXOOOOOOXXXXXXXXXXXSSSRXRRRRRXRF
+DDDDDTTTTTBBBBBMBBBBBBBBBBBBBKKKKOOOOOOOOOWWWWYWWXXKKKKSSSSSSSSSSSSSNNNNNYNNYYYYYYYAAAAAAAAAAGGMHXHHHMMMMMXXXXXXOQXXXXXNXXXXXHHPSSXXXXXXXXXX
+DDDDDDTTTTDDDDDBBBBBBBBBBBBBKKKKKOOOOOOOOOWWWWWWWXXXXKKTTSSSSSSSSSSSNNNNNYYYYYYYYYLAAAAAAGGAAGGGHHHHHFMMZMXXXXXQQQQXQXQQXXXBXPPPPXXXXXXXXXXX
+DDDDDDFFTTFSSSDBBBBBBBBBBBBBBBKKKKKOFFFOOOWWWWWWXXXXKKKKKKNSVSSSSSSSSNNNYYYYYYYYYAAAAAGGGGGGGGGGHHHHHHHZZZZXXXXQQQQQQQQQQXXBBBPPXXXXXXXXXXXX
+DDDDDFFFTTFFSSSBBBBBBBBBBBBBBKKKKKKOFFFFFOFWXXWXXXXKKKKKKNNSSSSSISSSSNNNYYYYYYYYYAAAAGGGGGGGGGGGHHHHHHHZZZZXZZQQQQQQQQQQQQQQBBPPXXXXXXXXXXXX
+DDDDDDDFFTFFAAVBBBBBBBBBBBBBBKBKKKKFFFFFFFFFXXXXXXXKKKKKKKNNNNNSSNSSSNNNNYYYYYYYYAYANYGYGYYYGGHHHHHHHHZZZZZZZZZQQQQQQQQQQQQQPPPPXXXXXXXXXXXX
+DDDDDDFFFFFFAAAABBBBBBBBSBBBBBBWWKKQFFFFFFFXXXXXXXXXKKKKKKNNNNSSSNSSSNNLNYYYYYYYYYYYYYYYYYYYGGHEHHHHHKKZZZZZZZZQQQQQQQQQQQQPPPPPXXXXXXXXXXXX
+DDDDFBFFFFFFAAAAABYBBBBBSSBXXXBWWQQQAFFFFFFXXXFFXXXXKKKKKKNNMNNNNNNNSNNNNYYYYYYYYYYYYYYYYYYGGGGHHHHHHKKKZZZZZZWQQQQQQQQQQBQPPPPPCCCCXXXXXXXX
+DDDFFFFFFFFFAAAABBYYBBBBSSBXXXXXWQQQFFFFFFFXXXFFXXXXXXKKKKNMMMNNNNNNNNNNNNYYYYYYYYYYYYYYYYYGGGGHHHHHHKKZZZZZWWWQQQQWQQQWQQPPPPPPCCCXXXXXXXXX
+DNDDFFFFFFFFAAAAABYYYBBBSSSXXXYXQQQQFFFFFFFFFQFFFFFFXXKKGGMMMMMFFNFNNNNNNNYYYYYYYYYYYYYYYYYGGGGGHHHHZZZZZZZZWFWQQQWWWWWWWWPPPCPPPCCXXXXXXXXC
+DNUUAFFFFFFFAAAAAAYYYBBBBBXXXXXDQQQQFQQFFFQQQQFFFFFMMMGGGGMMMMMFFFFFNNNNNNNTYYYYYYYYYYYYYYPGGGGHHHHHZZZZZWWWWWWAQWWWWWWWWWMCCCCCCCXXCXXXCXXC
+UUUUUFFFFFFFFAAAAYYYYYYBYYXXXDDDQQQQQQQQQFQQQQFFFFMMMMMGGMGFFFFFFFFNNNNNNHNTTTYYYYYYYYYYYYPPPPGHHHDZZZZZWWWWWWWWWWMWWWMMMMMMCCCCCCCCCXXXCCXC
+UUUUFFFFFFFFFFAAAYYYYYYYYYYYXDDQQQQQQQQQQQQQXXFFMMMMMMGGMMFFFFFFFFNNNNNNNDTTTTYYYYYYYYYYPPPPPPPPNNZZZUZUUWWWWWWWWWMMMMMMMMMMCCTTTTCCCXXPCCCC
+UUUUFFFFFFFFFFAAAAYYYYYYYYYYHHDQQQQQQQQQQQQQQQQMMMMMMMMGMCCFFFFFFFFNNNNDNDDDDDDCCAAYYYYYPPYYPPTTZZZZZZZZWWWWWWWWWMMMMMMMMMMMMCTNNNPPPPPPCCPC
+UUUUFFFFFFFFFFFFAAYYYYYYYYYHHHDQQQQQQQQQQQQQQMMMMMMMMMMMMCCFFFFFFFFNNDDDDDDDDDDCCAAAYYYYYYYYYYTSSSSSZZSHYWWWWWWWWMMMMMMMMMMMMMKPPNPPPPPPPPPP
+UUUUFFFFFFFFFFFFAYYYYYYYYYHHHHHQQKQQQQQQQQQQQQMMMMMMMMMMMMMFFFFFFFFMNDDDDDDDDDDCCCAAAAYYYYYYYYTSSSSSZZSSYYWYYYWWMMMMMMMMMMMMMMPPPPPPPPPPPPPQ
+UUUUUUFFFFFFFFFFFFQQQYYYYYHHHHHKKKQQQQQQQQQQQQMMMMMMMMMMMMFFFFFFFFFFNDDDDDDDDCCCAAAAAAYYYYYYYYYSSSSSSSSSYYYYYYWWWWMMMMMMMMMMMMMMPPPPPPPPPPPQ
+UUUUUUUFFFFQFFFQDQQQYYYYDHHHHHQHKKKKQQQQQQQQQQMMMMMMMMMMMUUFFFFFFFFNNNNDDDDDDCCAAAAAAAAYAYYYYYYSSSSSSSSSSYYYYYYWWQMMMMMMMMMMMMMMPPPPPPPPPPPP
+UUUUUUUFFFFQQQQQQQQQDDDDDHHHHHHHKKKKQQQQQQQQQQMMMMMMMMMMMUUFFFFFFFFNNNNNDDDDDCCAZAAAAAAAAYYYYYYSSSSSSSSSYYYYYYYYYPPPPMMMMMMMMMMKPPPPPPPPPPPP
+UUUUUUUFFFQQQQQQQQQQDDDDDDHHHHHHHHQQQQQQQQVQQMMMMMMMMMMMUUUUFFFFNNNNNNNNNDDCCCAAAAAAAAAAAYYYYYYYSSSSSSSSSYYYYYYYPPPPMMMMOMMMWWPPPPPPPPPPPPPP
+UUUUPPUUUUUUUQQQQDDDDDDDDHHHHHHHHBBBQQQQQQVMMMMMMMMMMMMMUUUFFFFFNNNNNNNNNNDCCAAAGAAAAAAAYYYYYGBBBSSSSSSSSSYYYYPPPPPPPMMPPPMMWWWPPPPPPPPPPPPP
+OUUUPPPPPIPPUQQQQLLLLDDHHHHHUUAAHBBBBBQBBBTBBBMMMMMMMGUUUUNNNFNFNNNNNNNNNNNCCCCAAAAAAAAAAYYYYBBBBSSSSSSSSSSYYYYPPPPPPPPPPPPMMWWWPPPPPPPPPMPP
+OUUUPPPPPPPPUQQLLLLHDDDHHHHHUUAUUUBBBBTBBBTBBBBMMGGMGGUUUUNNNNNNNNNNNNNNNNCCCCCAAAAAAAAAAYYYYBBBSSSSSSSSSSSSYYYCPPPPPPPPPPPWWWWPPPPPPPPPPMPP
+OOUPPPPPPPPPPLLLLLLHHHDDDHHUUUUUUUTTTTTBBBTTTBBBMGGGGGUUUUUNNNNNNNNNNNNNNNCCCCCCCAAAAAAAABCBBBBBSSSSSSSSCSSSSCCCPPWWPPPPPPWWWWPPPPPPPPPMMMMM
+OOUOOPPPPPPPPLLLLLLLHHHHHHUUUUUUUUTTTTTTTTTTTTBBBGGGGUUUUUUNNXNNNNNNNNNNNNCCCCCCAAAAAAAAABBBBBBSSSSSSSSSCSCCCCCCCCWWPPPPPPPWWWWWWPPPPPPMMMMM
+OOOOPPPPPPPPPLLLLLLHHHHHHHUUUUUUYYTTTTTTTTTTTTBGGZGGGUGGUUUNNNONNNNNNNNNNNNCCCCAAAAAAAAABBBBBBBSFFFFFFFFCSCCCCCCCCWWPPPPPPPWWWWWWPPPPPPMBMMT
+OOOPPPPPPPLLLLLLLLLLLLHHUUUUUUUUUTTTTTTTTTBBBTBBGGGGGGGGGGUUNNNNNNNNNNNNNNNCCCCCAAAAAAAAABBBBBBBFFFFFFFFCCCCCCCCWWWWPPPPPPPWWWWWUUPUUPMMMMMM
+OOOPPPPPPPPPLLLLLLHHLHHHUUUUUUUUUHHTTTTTTTBBBBBBGGGGGGGGGGGNNBNNNVNNNNNNNNNCCCCCCCAAAAHAAAABBBBSFFFFFFFFFFCCCCCCWWWWWWPPPWWWWWWUUUUUUMMMMMMM
+OPPPPPPPPPPPPLLLLLLHHHUUUUUUUUUUUUHTTNTBBTBBBGBBGGGGGGGGGGGBBBNNNNNNNNNNCNNCCCCCCAAAAHHVABBBBBBBBFFFFFFFFFCCCCCCWWWWWPPPPPWWWWWUUUUUUMMMMMMM
+YYXXPPPPPPHHHLHHLHHHHHRUFUUUUUUUHHHHTTBBBBBBBGGGGGGGGGGGGGGBBBNNNCCCCNCCCCCCCCCCCCHAAHJJJBBBBBBVCCCFFFFFFKKKKKKKKKKWWWPPPPWWUWWWUUUUUMMMMMMM
+YYYYDPPYPPHHHHHHHHHHRRRRFUUUUUUUUUWWTTBBBBBGGGGGGGGGGGGGGGGBBBBCCCAPCCCPCCCCCCCHCCHHHHJJJBBBBBBVCCCCCFFFFKKKKKKKKKKWWPPPPPWWUUUUUUUUUMMMMMMM
+YYYYYYYYPHHHHHHRRRRRRRRRUUUUUUUUUUWWBBBBBBBBGGGGGGGGGGGGGGGQBBQCCPPPPPCPPCCCCCCHHHHHHHJJJBBBBBBBCCCCCFFFFKKKKKKKKKKSPPPPJPWUUUUUUUUUUMMMMMMM
+YYYYYYYYYHHHHHHHHRRRRRRRRUUUUUUUWWWBBBBBBXXXSGGGGGWGWGGGGGGQQQQQKPPPPPPPPCCCCCCHHHHHHHJJJHHHHHBBCCCCCFFFFKKKKKKKKKKPPPPPPWWWUUUUUUUUMMMMMMMM
+YYYYYYYYYHHHHHHRRRRRRRRRRTTTUUUFWWWBBWWXXXXXSGGPWWWWWWPPGGQQQQQKKPPPPPPPPCCCCCCHHHHHHHJJJHHHHHBBCCCCCFFFFKKKKKKKKKKWPPPWWWWUUUUUUUUUMMMMMMMM
+YYYYYYYYYHHHHVHRRRRRRRRRRTTTUDWWWWWWWWWZXXXXSSGWWWWWWWPPGQQQQXQKPPPPPPPPPCCCCHHHHHHHHHJJJXXHHHHXCCXCCFFFFKKKKKKKKKKWWWWWWWWWUUUUUUMUMMMMMMMM
+YYYYYYYYYHHHVVHRRRRRRRRRRRTTTAWWWWWWWWWWXXXXXXTWWWWWWWWQQQQQQQQKPPPPPPPPPCCCHHAHHHHHHHJJJXXXHHXXXXXKKKKKKKKKKKKKKKKWWWZWWWWWWWWUMMMMMMMMMMMM
+VYYYYYYYYVVHVRRRRRRRRRRRRRRTTAAWWWWWWWWWXXXXXXXWWWWWWWWWWQQQQDDDDDDPPPPPPCCCCHHHHHHHHHJJJXXXXHHXXXXKKKKKKKKKKKKKKKKWWWZZZWWWWWWUHMMMMMMMMMMM
+YYYYYYYPPVVVVVVRRRRRRRRRRRRRTALWWWWWWWWWWXXXWWWWWWWWWWWWWQQQQDDDDDDPPPPPPPCCPHHHHHHHHXJJJXXXXXXXXXXKKKKKKKKKKKKKKKKWWZZZZZZZWWWUHMMMMMMMMMMM
+YYYYYYYYPPSSSVVVRBRRRRRRRAAAAALWWWWWWWWWWWXRWWWWWWWWWWWWWQQQQDDDDDDDPPPPPPCPPHHHHHHHXXJJJXXXXXXXXXCKKKKKKKKKIIIIIIWWWZZZZZZZWZZOZMMMMFFMMMMM
+TYYKYYXYPPSSWWVVBBBBBRRRAAAAAALWWWWWWWWWWQXRWWWWWWWWWWWWWQQQQDDDDDDPPPPPPPPPPHHHHHHHXXXXXXXXXXXXXXCKKKKKKKKKQQIIIIIWZZZZZZZZZZZZZOMMMMMMMMMM
+TTYYBYYPPPSSSWSBBBBBBGGGAAAAAALWWWWWWWWWWWRRRWWWWWWWWWWWUUUDDDDDDDDPPPPPPPPPPPHHHHHMXXXXXXXXXXXXXXCKKKKKKKKKQLIIIIIIIVZZZZZZZZZZPPMGGGGGGMMM
+TTYBBYQEPPPSSSSBBBBBBGGGAAAAALLWWWWWWWWRWRRRRWWWWWWWWWWWUUDDDDDDDDDPPPPPPPPPPPPHHHXXXXXXXXXXXXXXXXXKKKKKKKKKLLIIIIIPPZZZZZZZZZZZPPMGGGGGPMMM
+TTYBBYQEEPPSSSSSBBBGGGGGAAAAAGLLLWWWWRRRRRWWWWWWWWWWWWWWZUDDDDDDDDDDPPPPPIPPPPPPPHHXXXXXXXXXXXXXWXXKKKKKKKKKLLILMIPPPZZZZZZZZZZZPPPGGGGPPPPM
+TTTNNYQEPPPSSSSSBSGGGGGGGAGGAGLLWWWRRRRRRRWWWWWWWWWWUUWWZZZDDDDDDDDDDPIIIIIPPPPHHHHXXXXXXXXXXXXXWWLKKKKKKKKKLLLLMPPZZZZZZZZZZZZPPPPPPGPPYYPM
+TNNNEEEESSSSSSSSSSSSGGGGGGGGGGGLVVRRRRRRRRRWWWWWWWWUUUXZZZZDDDDDDDDDIIIIIIPPPPPPEQQXXUXXXXXXXXXXWWLLLLLLLLLLLLLLMPPXXZZZZZZZZZZPPPPPPPPPPYYY
+TNNNEEEESSSSSSSSSSSGGGGGGGGGGGLLVVVRRRRRRRRRWWWRWWUUUUZZZZDDDDDDDUDIIIIIIPPPPPPEEEEYXUUXXXXXKXXXWWWLLLLLLLLLLLMPPPPAXZZZZZZZZZPPPPPPPPPPPPPY
+TNNNNEEESSSSSSSSSSSGGGGGGGGGGGLLLLZZZZZRZRRWWWRRUUUUUUZZZZQDDDDBBUIIIIIIIIPPPEEEEEEEEEEEXKKKKKXWWWWWWLLLLLLLLPLTTTPAAZZZZZZZZZZPPPPPPPPPPPPP
+TTNNEEEEESSSSSSSSSSSGGGGGGGGGGGLLLRRZZZZZZRWRRRRUUUUUUUQZQQBBBDBBBIIIIIIIIIPPEEEEEEEEEEEECCKKKKGGWWWWLLLLLLLLLLTTTTAAAAZZZZZZZPPPPPPPPPPPPPP
+TNNNEEEEESSSSSSSSSSSSGGGGGGGGGGGLRRRRZRRRRRRRRRRUUUUUUUQQQBBBBDBBIIBIIIIIIUEEEEEEEEEEEEYYKCCKKKKGWWWLLLLLLLLLEEVTAAAAAAZSSZZZZPPPPPPPPPPPPCP
+TTNEEEEEESSSSSSSSJJJGGGGGGGGLGGLLRRRRZRRRRRRRRRRUUUUUUUUUQBBBBBBBBIBIIIIIIUUEEEEEEEEEEEEKKCKKKKKKKKKKLLLLLLLLLVVVAZZAAAVKKZPPPPPPPPPPPPPPPPP
+ENNEEEEERSSSSSSSSSJGGGGGGGGGLGGGGURRRRRRRRRRRRRUUUUUUUUUUUBBBBBBBBBBIIIIIUUUUEEEEEEEEEEEKKKKKKKKKKKKKKKLLLLLLLVVZZZZZAAVKEPPPPPPPPPPPPPPPPPP
+EEEEEEEERSSSSSSSJJJJGJGGJGLLLJJGGGRRRRRRRRRRRRRRRUUUUUUUUUBBBBBBBBBBBBIIUUUUUEEEEEEEEEYKKKKKKKKKKKKKKBBBLLLLVVVVEEZZZZAKKEPPPYPPPPPPPPPPPPPP
+EEEEEEEESSSSSSSJJJJJJJJJJJJLJJGGGGGRRRRRRRRRRRRRUUUUUUUZZUBBBBBBBBBBBBIBBBUUUEEEEEEEEEYKKKKKKKKKKKKKKBKLLVVVVVVVEEEZEEAEXPPPXXXNPPPPPPPPPCPW
+EEEEEEESSSISJJSJJJJJJJJJJJJJJJJGGGGGRRRRRRRRRRBUUUUUUUUZZZBBBBBBBBBBBBBBBBUCUUUEEEEDDDKKKKKKKQKKKKKKKKKVVVVVVVVVVEEEEEEEXXXXXXXXBPPPPPPPPPPW
+EEEEEEEESEEJJJJJJJJJJJJJJJJJJJGGGGOGGGRRRRRRBBBBBUUUUUUUUUEBBBBBBBBBBBBBBBUCCCCEEEEEDDKKKQKQQQKKKKKKCCBVVVVVVVVVVEEEEEEEXXXXXAABBBBPMMPWWWWW
+EEEEEEEESEEEJJJJJJJJJJJJJJJJJJGJGGGGGGRRRRRRBBBBBBBUUIIUEEEEBBBBBBBBBBBBFMUUCCCCCCCDDDDQCQKQUQQKKKKKCBBVVVVVVVVVVEEEEEWEXXXXXAAAAABMMMMMMWWW
+EEEEEEEEEEEEJJJJJJJJJJDJDJJJJGGGGGGGGGGYYYYRBBBBBBBBBBBEEEEEEOOBBBBBBBBBMMMCCCCCCCCCDDDQCQQQQQTKKKKKKUBVVVVVVVVVEEEEEEEZXXXXXAAALMMMMMOMWWWW
+EEEEEEEEEEJJJJDJDDDDDDDDDJJJJJAAGGGGYYYYYYYYYBBBBBBWWBEEEEEEEOOOOBBBRRRZZZZZZZZZZCCCCCDQCQQQQTTTKKKKKUBVVVVVVVVVEEEEEEEEUXXXXAAMMMMMMMMMMWWW
+EEEEEEEEEEEJJJDJDDDDDDZDDDJJJAAAAGGGGYYYYYYYYBBBBBBBWBBEEEEOOOOOOORRRRRZZZZZZZZZZCCCDDDQQQQQQQQTTKKKKKBBBVVVVVVVEEEEEEEEUUXXXSSSSMMMNMZMWWWW
+ESEESEEEEEEEEDDDDDDDDDDDDDJJAAAAAAAAYYYYYYYBBBBBBBBBBBBBBBEOOOOOORRRRRRZZZZZZZZZZCCCDDQQQQQQQQQTTKKKKBBBBBVVVVUEEEEEEEEEEXXXXXSMMMMNNNNMMWWW
+ESSSSEEEEEEEEADDDDDDDDDDDJJJAAAAAAAYYYYYYYYBBBBBBBBBBBBBBBEEEOOORRRZZZZZZZZZZZZZZOCCDDQGIQQQQQQQTQQBBBBBBBVVVUUUEEEEEEEEEEXTXXSSSNNNNWWWWWWW
+ESSSSSSSEEESDDDDDDDDDDDDJJJJAAAAAAAAYYYYYYYYBYBBBBBBBBBBBEEEOOOORRRZZZZZZZZZZZZZZKDDDGGGQQQQQQQQQQQBBBBBBBVUUUUUEEEEEEEEEEETXSSSNNLNNNNNNWWW
+SSSSSSSSSSSSDDDHDDDDDDDDJAAAAAIAAAAAYYYYYYYYYYYBBBBBBBBEEEEEOOOORRRZZZZZZZZZZZZZZKDDGGGGQQQQQQBQQQBBBBBBNNBRUUUURRREEEEEEEETTNNNNNNNNNNNNTWW
+SSSSSSSSSSSDDDDDDDDDDDDJAAAAAAAAAAAYYYYYYYYYYYBBBBBBBGGGEEEEOOOORRKZZZZZZZZZZZZZZGGGGGGGQQQQQQBBBBBBBBBBBBBRRRRRRRRREENNENNNNNNNNNNNNNNNNTWW
+SSSSSSSSSSDDDDDDDDDDDDAAAAAAAAAAAAAYYYYYYYYYYBBBBBBBBGGGGEEEOOOOTRRZZZZZZZZZZZZZZKKGGGGFQQQRRQBBBBBBBBBRRRRRRRRRRRRREENNNNNNNNNNNNNNNNNNNTTT
+SSSSSSSSSSDDDDDDDDDDDDAAAAAAAAAAAAAAYYYYYYYYYYBBBBBGBGGGGEEEEOTTTTRZZZZZZZZZZZZZZZKGGGGFQQRRRQBBBBBXBBXRRRRRRRRRRRRNNENNNNNNNNNNNNNNNNNTTTTT
+SSSSSSSSSSDDDDDDDDDDDDAAAAAAAAAAAAAYYYYYYYYYYJBBBBBGGGGGGEEEETTTTTTZZZZZZZZZZZZZZZKKKKFFQBBBBBBBXXXXXXXXXRRRRRRRRRNNNENNNNNNNNNNNNNNNNNNTTTT
+SSSHSHSSHSSDDDDHHHHDDDAAZAAAAAAAAYYYYYYYYYYYYNXBBBBGGGGGGGETTTTTTTTTEEVVZZZZZZZZZZKKKKFFBBBBBBBXXDXXXXXXXXXRRRRNNRNNNNNNNNNNNNNNNNNNNNTTTTTT
+SSHHHHHHHSSDDHHHHHBHDHHAAAAAAAAAAYYYYYYYYYYYYNXNIBIIGGGGGGTTTTTTTTTTEVVVZZZZZZZZZZKKFFFBBBBBBBBXXXXXXXXXXXXRRRRNNNNNNNNNNNNTNNNNYNTTNNTTTTTT
+SSSHHHHHHSSSDHHHHHHHHHHCCAAAAAACCYYYYYYYYYYNYNNNIIIIGGGYGGFTTTTTTTTVVVVVVVVKKKKKKKKKFBBBBBBBBBBBXXXXXXXXXUXRRRRRNNRRNNNNNNNTNNNNTNTNNNTTTTTT
+SSSHHHHHHHHSHHHHHHHHHHHHCAAAAAACCYYYYYNYYYYNNNNPPPIGGGGGGGGTTTTTTVTVVVVVVVVKKVKKKKKKFFBBBBBBBJXBXXXXXXXXXXXRNNNRRNNRNNNNNNRTNNNNTNTNTNTTTTTT
+SSHHHHHHHHHHHHHHHHHHHHHCCCCAACCCCCNWNNNNYYYNNNNNPPPPGGGIIITTTTTTVVVVVVVVVVVVVVKKKKKKKFBBBBBBBJXXXXXXXXXXXXXNNNNNRRRRNNNNNNRTTTTTTTTTTTTTTTTT
+HHHHHHHHHHHHHHHHHVHHVVCCCCCCCCCCCCNNNNNNNNNNNNNNPPPPPPPIIIITITVVVVVVVVVVVVVVVVKKKKKKKBBBBBBBOBXXXXXXXXXXXXXNNNNNRNRRNNNNNRROOTTTTTTTTTTTTTTT
+HHHHHHHHHHHHHHHHHVVVVVCCCCCCCCCCCCNKNNNNNNNNNPPPPPPPPPPIIIIIIIIVVVVVVVVVVVVVVKKKKKKKBBBBBBBBBBBXXXXXXXXXONNNNNNNNNRRNNNNNNROOTTTTTTTTTTTTTTT
+HHHHHHHHHHHHHVVVVVVVFVVVCCCCCKKKCNNKNNNNNNNNNPPPPPPPPPPPPIPIIIIVVVVVVVVVVVVVKKKKKKKBBBBBBBBBBBBXXXXXXXXXXNNNNNNNNNNRRNNNNNNOOTTTTTTTTTTTTTTT
+HHHHHHHHFFHFVVVVVVVVVVVCCCCCCKKKKNNNNNNNNNNNNNPPPPPPPPPPPPPIIIIVIVUVVVVVVVVVKKKKKKBBBBBBBBBBBBBBXXXXXXXXNNNNNNNNNNNNNBNOONNOOOTZZTTTTTTTTTTT
+HHUHHHHHFFFFVVVVVVVVVVVVCCCCCKKKMNNNNNNNNNNNNNNPPPPPPPPPPPPIIIIIIIVVVVVVVVVVKKKKKKBBBBBBBBBBBBPBPPXXPPPXNNNNNNNNNNNOOOOOOOOOOOOOZZZZZTTTTTTT
+HHHFFFHHFFFFVVVVVVVVVVVCCCCCCKKKKXNNNNNNNNNNNNNNPPPPPPPPPPIIIIIIIIIIVVIVVIIKKKKKKGGGBBBBBBBBBBPPPPXXXPNNNNNNNNNNNNNNOOOOOOOOOOZZZZZZZTTTTTTT
+FFFFFFHHFFFFFFVVVVVVVVCCCCCKKKKKKKKNNNNNNNNNNNPPPPPPPPPPPPIIIIIIIIIIVIIIIIIIKKKKGGGGBBBBBBQBBBPPPPXXPPNNBBNNNNNNNNNNNNWOOOOOOOEEEZZZZTTTTTTT
+FFFFFFFFFFFFFFFVVVVVVVCCCCKKKKKKKHKKKKWNNNNNNNPPPPPPIIIIIIIIIIIIIIIIIIIIIIIIKKKGGGGGBPPBHBQBBPPPPPPPPNNNBBNNNNNNNNNNNNOOOOOOOOOEEEZZZTTTTTTT

solutions/solutions.cabal

@@ -1167,3 +1167,8 @@ executable sln_2024_11
   import:              day
   main-is:             2024/11.hs
   build-depends:       containers
+
+executable sln_2024_12
+  import:              day
+  main-is:             2024/12.hs
+  build-depends:       containers

solutions/src/2024/12.hs

@@ -0,0 +1,55 @@
+{-# Language BlockArguments, ImportQualifiedPost, MonadComprehensions #-}
+{-|
+Module      : Main
+Description : Day 12 solution
+Copyright   : (c) Eric Mertens, 2024
+License     : ISC
+Maintainer  : emertens@gmail.com
+
+<https://adventofcode.com/2024/day/12>
+
+-}
+module Main (main) where
+
+import Advent (getInputMap, countBy)
+import Advent.Coord (Coord, cardinal, above, right, below, left)
+import Advent.Search (dfs)
+import Data.List (unfoldr)
+import Data.Map (Map)
+import Data.Map qualified as Map
+import Data.Set (Set)
+import Data.Set qualified as Set
+
+-- | >>> :main
+-- 1546338
+-- 978590
+main :: IO ()
+main =
+ do input <- getInputMap 2024 12
+    let rs = regions input
+    print (sum (map (\x -> perimeter x * length x) rs))
+    print (sum (map (\x -> walls     x * length x) rs))
+
+-- | Return a list of regions in the input map.
+regions :: Map Coord Char -> [Set Coord]
+regions = unfoldr \input ->
+  [ (region, Map.withoutKeys input region)
+  | (start, label) <- Map.lookupMin input
+  , let region = Set.fromList (dfs step start)
+        step i = [j | j <- cardinal i, Map.lookup j input == Just label]
+  ]
+
+
+-- | Find the perimeter length of a region.
+perimeter :: Set Coord -> Int
+perimeter xs = length [() | x <- Set.toList xs, y <- cardinal x, y `Set.notMember` xs]
+
+-- | Compute the number of walls needed to surround a region by looking for
+-- the corners of the region.
+walls :: Set Coord -> Int
+walls xs =
+  let f i = Set.member i xs in
+  countBy (\x -> not (f (above x)) && (not (f (right x)) || f (above (right x)))) xs +
+  countBy (\x -> not (f (below x)) && (not (f (right x)) || f (below (right x)))) xs +
+  countBy (\x -> not (f (right x)) && (not (f (above x)) || f (above (right x)))) xs +
+  countBy (\x -> not (f (left  x)) && (not (f (above x)) || f (above (left  x)))) xs