#include <iostream>
using namespace std;
int main(){
  long long l,r,m,k;cin>>l>>r>>m>>k;
  long long mn = l*k;
  long long mx = r*k;
  if(!(mn%m) || (mx/m != mn/m)){
    cout << "Yes" << endl;
  }else{
    cout << "No" << endl;
  }
}