#include <stdio.h>

int main(void)
{
	long h, w, n, k;
	scanf("%ld%ld%ld%ld", &h, &w, &n, &k);
	puts(h * w % n ? h * w / n == k ? "YES" : "NO" : h * w / n == k ? "NO" : "YES");
	return 0;
}