Codeforces Round #460 (Div. 2), problem: (C) Seat Arrangements

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define pli pair<long long int,int>
#define pbi pair<bool,int>
#define pob pop_back
#define all(a) a.begin(),a.end()
#define fio ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0);
#define i64 long long int
#define mem(x,y) memset(x,y,sizeof(x))
#define fill(arr,b) fill(arr, arr+sizeof(arr)/sizeof(arr[0]), b)
#define maxarr(n,arr,m) m =-1e9;for(int i=0;i<n;i++)if(arr[i]>m) m=arr[i];
#define read freopen("input.txt","r",stdin);

const double pi = acos(-1.0);
const int maxn = (i64)1e9+7;
bool s[2005][2005];
int main()
{
   //read;
   int n,m,k;
   scanf("%d%d%d",&n,&m,&k);
   char c;
   for(int i=0;i<n;i++)
   {
      getchar();
      for(int j=0;j<m;j++)
      {
          scanf("%c",&c);
          if(c=='*')s[i][j]=1;
          else s[i][j]=0;
      }
   }
   int ans=0;
   for(int i=0;i<n;i++)
   {
       int cnt=0;
       for(int j=0;j<m;j++)
       {
           if(s[i][j]==1)cnt=0;
           else cnt++;
           if(cnt>=k)ans++;
       }
   }
   for(int i=0;i<m;i++)
   {
       int cnt=0;
       for(int j=0;j<n;j++)
       {
           if(s[j][i]==1)cnt=0;
           else cnt++;
           if(cnt>=k)ans++;
       }
   }
   if(k==1) ans/=2;
   printf("%d",ans);

   return 0;
}