func_code_string: #include <bits/stdc++.h>   using namespace std;   string a[2006];   int row[2006], cal[2006];   int w[2006];   int main() {     int n, ans = 0;     cin >> n;     for (int i = 0; i < n; i++) cin >> a[i];     for (int i = n - 1; i >= 0; i--) {       for (int j = 0; j < i; j++) {         int t = cal[j] + row[i];         if ((t % 2 == 0 && a[i][j] ==  1 ) || (a[i][j] ==  0  && t % 2 == 1)) {           cal[j]++;           row[i]++;           ans++;           w[j]++;           w[i]++;         }       }     }     for (int i = 0; i < 2006; i++) row[i] = cal[i] = 0;     for (int i = 0; i < n; i++) {       for (int j = n - 1; j > i; j--) {         int t = cal[j] + row[i];         if ((t % 2 == 0 && a[i][j] ==  1 ) || (a[i][j] ==  0  && t % 2 == 1)) {           cal[j]++;           row[i]++;           ans++;           w[j]++;           w[i]++;         }       }     }     for (int i = 0; i < n; i++)       if ((a[i][i] ==  1  && w[i] % 2 == 0) || (a[i][i] ==  0  && w[i] % 2 == 1))         ans++;     cout << ans << endl;     return 0;   }   