#include <stdio.h>

int main(void){
    int W, H;
    long long int N, k, K;
    scanf("%d %d %lld %lld", &W, &H, &N, &K);
    if(W*H<=N){
        k = N;
    }else{
        k = W*H%N;
    }
    if(k==K){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
    return 0;
}