#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
const long long MAX = 2e6 + 7;
const long long dx[8] = {-1, -1, -1, 0, 1, 1, 1, 0};
const long long dy[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
long long i, j, k, t, n, q, l, r, mid;
long long m, x, y, yy;
long long flag;
set<long long> st;
void solve() {
  cin >> n >> m >> x >> y;
  for (long long i = 1; i < m + 1; i++)
    if (i != y) st.insert(i);
  cout << x << " " << y << endl;
  for (long long i = 1; i < n + 1; i++) {
    if (i != x) cout << i << " " << y << endl;
  }
  flag = 0;
  while (st.size()) {
    yy = *st.begin();
    st.erase(yy);
    if (flag == 0) {
      for (long long i = n; i >= 1; i--) cout << i << " " << yy << endl;
    } else
      for (long long i = 1; i < n + 1; i++) cout << i << " " << yy << endl;
    flag ^= 1;
  }
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  solve();
  return 0;
}
