#include <bits/stdc++.h>
using namespace std;
long long int ar[509][509], cr[500009], br[500009], tr[500009];
long long int fx[] = {-1, 1, 0, 0};
long long int fy[] = {0, 0, 1, -1};
map<long long int, long long int> mp;
vector<long long int> v[500009];
string s, q, r;
int main() {
  long long int a, b, c, d, e, i, j, k, x, y, z, f, g, h, n, m;
  {
    cin >> n >> m;
    cin >> x >> y;
    cout << x << " " << y << endl;
    ar[x][y] = 1;
    k = 1;
    while (1) {
      for (j = 1; j <= m; j++) {
        if (ar[x][j] == 0) {
          k++;
          y = j;
          cout << x << " " << j << endl;
          ar[x][j] = 1;
        }
      }
      for (j = 1; j <= n; j++) {
        if (ar[j][y] == 0) {
          k++;
          x = j;
          cout << j << " " << y << endl;
          ar[j][y] = 1;
        }
      }
      if (k == (n * m)) {
        break;
      }
    }
  }
}
