#include<bits/stdc++.h> 
using namespace std;
typedef long long ll;
template<typename T1,typename T2> bool chmin(T1 &a,T2 b){if(a<=b)return 0; a=b; return 1;}
template<typename T1,typename T2> bool chmax(T1 &a,T2 b){if(a>=b)return 0; a=b; return 1;}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);

    ll l,r,m,k;
    cin>>l>>r>>m>>k;
    ll dif = r*k - l*k;
    ll mini = l*k;
    mini %= m;
    if(m==0 || (m-mini)+dif>=m)cout << "Yes\n";
    else cout << "No\n";
}