#include<bits/stdc++.h>
using namespace std;
int main(){
    long l,r,m,k;
    cin >> l >> r >> m >> k;
    bool chk = false;
    if((l*k)%m == 0 ||(r*k) - (l*k) >= m ||(r*k)%m < (l*k)%m)chk=true;

    if(chk)cout<<"Yes"<<endl;
    else cout<<"No"<<endl;
}