func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   char s[2001][2002];   int wu[2][2001];   int ans;   int main() {     scanf( %d , &n);     for (int i = 1; i <= n; i++) scanf( %s , s[i] + 1);     for (int i = 1; i <= n; i++) {       int rxor = 0, lxor = 0, d;       for (int j = n; j > i; j--) {         d = wu[0][j] ^ (s[i][j] -  0 ) ^ rxor;         if (d) ans++, rxor ^= 1, wu[0][j] ^= 1;         d = wu[1][j] ^ (s[j][i] -  0 ) ^ lxor;         if (d) ans++, lxor ^= 1, wu[1][j] ^= 1;       }       if ((s[i][i] -  0 ) ^ rxor ^ lxor ^ wu[0][i] ^ wu[1][i]) ans++;     }     cout << ans << endl;     return 0;   }   