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