#include <stdio.h> 
#include <math.h>

int main(){
	int TakahashiBlood,TakahashiAttack,AokiBlood,AokiAttack;
	scanf("%d %d %d %d",&TakahashiBlood,&TakahashiAttack,&AokiBlood,&AokiAttack);
	if((TakahashiBlood/AokiAttack)>(AokiBlood/TakahashiAttack))
		printf("Yes");
	else if((TakahashiBlood/AokiAttack)==(AokiBlood/TakahashiAttack)){
		if((TakahashiBlood-(AokiAttack*(floor(TakahashiBlood/AokiAttack))))!=0)
			printf("Yes");
		else if ((AokiBlood-(TakahashiAttack*(floor(AokiBlood/TakahashiAttack))))==0)
			printf("Yes");
		else
			printf("No");
	}
	else
		printf("No");
}