#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, m, a, b, temp = m;
  cin >> n >> m >> a >> b;
  vector<vector<long long>> visited(n + 1, vector<long long>(m + 1, 0));
  visited[a][b] = 1;
  cout << a << " " << b << endl;
  for (int i = 1; i <= m; i++) {
    if (!visited[a][i]) {
      visited[a][i] = 1;
      cout << a << " " << i << endl;
    }
  }
  temp = m;
  for (int i = m; i >= 1; i--) {
    if (temp == 1) {
      for (int j = 1; j <= n; j++) {
        if (!visited[j][i]) {
          cout << j << " " << i << endl;
          visited[j][i] = 1;
        }
        temp = j;
      }
    } else {
      for (int j = n; j >= 1; j--) {
        if (!visited[j][i]) {
          cout << j << " " << i << endl;
          visited[j][i] = 1;
        }
        temp = j;
      }
    }
  }
}
int main() { solve(); }
