#include<stdio.h>
int main(void)
{
	int a,b,c,d,t,o;
	scanf("%d %d %d %d",&a,&b,&c,&d);
	while(1){
		t=a-d;
		o=c-b;
		if(t<=0){
			printf("no\n");
			break;
		}
		else{
				o=c-b;
				t=a-d;
				if(o<=0){
					printf("yes\n");
					break;
				}
			}
		}	
	}
	return 0;
}