#include <bits/stdc++.h>   using namespace std;   int main() {     int n, m, x, y, i;     cin >> n >> m >> x >> y;     cout << x <<     << y << endl;     int a = x;     for (i = 1; i < m + 1; i++) {       if (i != y) {         cout << x <<     << i << endl;       }     }     n++;     int cnt = 0;     while (n-- && n > 0) {       if (n != x) {         cnt++;         if (cnt % 2) {           for (int i = m; i > 0; i--) {             cout << n <<     << i << endl;           }         } else {           for (i = 1; i < m + 1; i++) {             cout << n <<     << i << endl;           }         }       }     }     return 0;   }   