#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000

int main(){

	long long L,R,M,K;
	cin>>L>>R>>M>>K;
	
	L*=K;
	R*=K;
	
	if(L%M==0||R%M==0||L/M!=R/M){
		cout<<"Yes"<<endl;
	}
	else{
		cout<<"No"<<endl;
	}
	
	return 0;
}