#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
int main() {
  long long H,W,N,K; cin >> H >> W >> N >> K;
  long long HW = H * W;
  long long ans = HW % N;
  if(ans == 0) {
    ans = N;
  }
  
  if(ans == K) {
    cout << "YES" << endl;
  }else {
    cout << "NO" << endl;
  }
}