#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
  ll h, w, n, k;
  cin >> h >> w >> n >> k;
  ll t = h * w;
  if (n == k) k = 0;
  if (t % n == k) {
    puts("YES");
  } else {
    puts("NO");
  }
  return 0;
}