#include <stdio.h>

int main() {
    int h, w, n, k, l, m;

    scanf("%d %d %d %d", &h, &w, &n, &k);
    m = h * w;
    l = m % n;
    
    if ((l == 0 && k == n) || (l == k))
        printf("yes\n");
    else
        printf("no\n");

    return 0;
}