#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<cstdio>
using namespace std;
int main(){
    long long H,W,N,K,num;
    cin >> H >> W >> N >> K;
    num = (H*W)%N;
    if(num==0)  num+=N;
    if(num==K)  cout << "YES";
    else    cout << "NO";
    return 0;
}