func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, mn = 2e9, cnt, num, s[2505][2505];   bool v[2505];   char a[2505][2505];   int main() {     int i, j, r, c, tr, tc, sz;     cin >> n >> m;     for (i = 1; i <= n; i++) {       scanf( %s , &a[i][1]);     }     for (i = 1; i <= n; i++) {       for (j = 1; j <= m; j++) {         s[i][j] = s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1] + a[i][j] -  0 ;       }     }     sz = max(n, m);     for (i = 2; i <= sz; i++) {       cnt = 0;       for (r = 1; r <= n; r += i) {         for (c = 1; c <= m; c += i) {           tr = min(r + i - 1, n);           tc = min(c + i - 1, m);           num = s[tr][tc] - s[r - 1][tc] - s[tr][c - 1] + s[r - 1][c - 1];           cnt += min(num, i * i - num);         }       }       mn = min(mn, cnt);     }     cout << mn;     return 0;   }   