#include <stdio.h>

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