#include <bits/stdc++.h>
using namespace std;
int n, m, x, y;
int main(void) {
  scanf("%d%d%d%d", &n, &m, &x, &y);
  printf("%d %d\n", x, y);
  if (y != 1) printf("%d %d\n", x, 1);
  int mode = 0, i, j;
  for (i = 1; i <= m; i++) {
    if (!mode) {
      for (j = 1; j <= n; j++) {
        if ((j == x && i == y) || (j == x && i == 1)) continue;
        printf("%d %d\n", j, i);
      }
      mode = 1;
    } else {
      for (j = n; j >= 1; j--) {
        if ((j == x && i == y) || (j == x && i == 1)) continue;
        printf("%d %d\n", j, i);
      }
      mode = 0;
    }
  }
  return 0;
}
