#include <bits/stdc++.h>   using namespace std;   int main() {     int n, m, x, y;     cin >> n >> m >> x >> y;     int vis[105][105];     int i, j;     for (i = 0; i < 105; i++)       for (j = 0; j < 105; j++) vis[i][j] = 0;     vis[x][y] = 1;     cout << x <<     << y << endl;     cout << x <<     << m << endl;     for (i = x - 1; i >= 1; i--) cout << i <<     << m << endl;     for (i = x + 1; i <= n; i++) cout << i <<     << m << endl;     int flag = 1;     for (i = m - 1; i >= 1; i--) {       if (flag) {         for (j = n; j >= 1; j--) {           if (vis[j][i] == 0) {             cout << j <<     << i << endl;             vis[j][i] = 1;           }         }         flag = !flag;       } else {         for (j = 1; j <= n; j++) {           if (vis[j][i] == 0) {             cout << j <<     << i << endl;             vis[j][i] = 1;           }         }         flag = !flag;       }     }   }   