#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using f64 = double;
using f80 = long double;
using pii = pair<int, int>;
using ptx = pair<f64, f64>;
const int N = 105;
bool f[N][N];
int n, m, first, second;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  int tip = 1;
  int a, b;
  cin >> n >> m;
  cin >> first >> second;
  cout << first << ' ' << second << '\n';
  f[first][second] = true;
  for (int j = 1; j <= m; ++j) {
    if (!f[first][j]) {
      cout << first << ' ' << j << '\n';
      f[first][j] = true;
      a = first, b = j;
    }
  }
  tip = -1;
  for (int i = 1; i <= n; ++i)
    if (!f[i][m] && !f[i][1]) {
      for (a = i; true; b += tip) {
        cout << a << ' ' << b << '\n';
        f[a][b] = true;
        if (!(1 <= b + tip && b + tip <= m)) break;
      }
      tip *= -1;
    }
  return 0;
}
