#include <bits/stdc++.h>
using namespace std;
int n, m, r, c, b, cr, s;
void run() {
  long long cnt = 0;
  cout << cr << ' ' << b << endl;
  int i = b;
  while (cnt < (m - 1)) {
    i += s;
    cout << cr << ' ' << i << endl;
    cnt++;
  }
  b = i;
  cr++;
}
int main() {
  cin >> n >> m >> r >> c;
  int i = 0;
  cout << r << ' ' << c << endl;
  for (i = 1; i <= m; ++i) {
    if (i != c) cout << r << ' ' << i << endl;
  }
  cr = r + 1;
  b = m;
  while (cr <= n) {
    s = -1;
    run();
    if (cr > n) break;
    s = 1;
    run();
  }
  cr = 1;
  while (cr < r) {
    if (s == 1)
      s = -1;
    else
      s = 1;
    run();
    if (cr >= r) break;
    if (s == 1)
      s = -1;
    else
      s = 1;
    run();
  }
}
