func_code_string: #include <bits/stdc++.h>   using namespace std;   const int64_t N = 1e3 + 5, M = 1e9 + 7;   int64_t a[N][N];   int main() {     ios::sync_with_stdio(0), cin.tie(0);     int64_t n, m, s = 0;     cin >> n >> m;     for (int64_t i = 0; i < n; i++)       for (int64_t j = 0; j < m; j++) cin >> a[i][j];     for (int64_t i = n - 2; i; i--)       for (int64_t j = m - 2; j; j--)         if (!a[i][j]) a[i][j] = min(a[i + 1][j], a[i][j + 1]) - 1;     for (int64_t i = 0; i < n; i++)       for (int64_t j = 1; j < m; j++)         if (a[i][j] <= a[i][j - 1]) return cout << -1, 0;     for (int64_t j = 0; j < m; j++)       for (int64_t i = 1; i < n; i++)         if (a[i][j] <= a[i - 1][j]) return cout << -1, 0;     for (int64_t i = 0; i < n; i++)       for (int64_t j = 0; j < m; j++) s += a[i][j];     cout << s;   }   