#include <stdio.h>

int main(void){
    int W, H;
    long long int N, lose, K;
    scanf("%d %d %lld %lld", &H, &W, &N, &K);
    lose = W*H % N;
    if(lose==0) lose = N;

    if(K==lose){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
    return 0;
}