#include <stdio.h>

int main()
{
	int a, b, c, d;

	scanf("%d %d %d %d", &a, &b, &c, &d);

	// takashi  a b
	// aoki c d

	int taka_turn = 1;

	while (true) {
		if (taka_turn) {
			c -= b;
			taka_turn = 0;
		}

		else {
			a -= d;
			taka_turn = 1;
		}

		if (a == 0) {
			printf("No\n");
			return 0;
		}

		if (c == 0) {
			printf("Yes\n");
			return 0;
		}
	}

	return 0;
}