#include <stdio.h>
#include <string.h>
#include<stdbool.h>
#include<stdlib.h>

int people[2][2];

char str[1000];

int main(void) {

	fgets(str, sizeof(str), stdin);

	sscanf(str, "%d %d %d %d", &people[0][0], &people[0][1], &people[1][0], &people[1][1]);

	bool win = false;

	while (true)
	{
		for (int p = 0; p < 2; p++) {

			people[1 - p][0] -= people[p][1];

			if (people[1 - p][0] <= 0) {

				if (p == 0) {
				
					printf("%s\n", "Yes");
				
					return 0;

				}
				else
				{
					printf("%s\n", "No");

					return 0;

				}

			}

		}



	}

}