func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m, i, j, sum = 0, x, y, b;     cin >> n >> m;     int a[n][m];     vector<pair<int, int>> v;     for (i = 0; i < n; i++) {       for (j = 0; j < m; j++) {         cin >> a[i][j];         sum += a[i][j];         if (a[i][j] == 0) v.push_back(make_pair(i, j));       }     }     for (i = v.size() - 1; i >= 0; i--) {       x = v[i].first;       y = v[i].second;       a[x][y] = min(a[x + 1][y], a[x][y + 1]);       a[x][y] -= 1;       sum += a[x][y];     }     for (i = 0; i < n - 1; i++) {       for (j = 0; j < m - 1; j++) {         if (a[i][j] >= a[i + 1][j] || a[i][j] >= a[i][j + 1]) {           cout << -1;           return 0;         }       }     }     for (i = 0; i < m - 1; i++) {       if (a[n - 1][i] >= a[n - 1][i + 1]) {         cout << -1;         return 0;       }     }     for (j = 0; j < n - 1; j++) {       if (a[j][m - 1] >= a[j + 1][m - 1]) {         cout << -1;         return 0;       }     }     cout << sum;   }   