#include <bits/stdc++.h>
using namespace std;
int main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m, x, y;
  cin >> n >> m >> x >> y;
  cout << x << " " << y << "\n";
  for (int i = 1; i <= n; i++)
    if (i != x) cout << i << " " << y << "\n";
  int dir = 0;
  for (int i = 1; i <= m; i++) {
    if (i == y) continue;
    if (dir == 0) {
      for (int j = n; j >= 1; j--) cout << j << " " << i << "\n";
      dir = 1;
    } else {
      for (int j = 1; j <= n; j++) cout << j << " " << i << "\n";
      dir = 0;
    }
  }
  return 0;
}
