func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n >> m;     vector<vector<int>> a(n, vector<int>(m, 0));     vector<vector<int>> b(n, vector<int>(m, 0));     for (int i = 0; i < n; i++) {       for (int j = 0; j < m; j++) {         cin >> a[i][j];       }     }     vector<pair<int, int>> ans;     for (int i = 0; i < n - 1; i++) {       for (int j = 0; j < m - 1; j++) {         if (a[i][j] == 1 && a[i][j + 1] == 1 && a[i + 1][j + 1] == 1 &&             a[i + 1][j] == 1) {           ans.push_back(make_pair(i, j));           b[i][j] = 1;           b[i][j + 1] = 1;           b[i + 1][j + 1] = 1;           b[i + 1][j] = 1;         }       }     }     bool flag = true;     for (int i = 0; i < n; i++) {       for (int j = 0; j < m; j++) {         if (a[i][j] != b[i][j]) {           flag = false;           i = n;           break;         }       }     }     if (flag) {       cout << ans.size() << endl;       for (auto it = ans.begin(); it != ans.end(); it++) {         cout << (*it).first + 1 <<     << (*it).second + 1 << endl;       }     } else       cout << -1 << endl;     return 0;   }   