/*** author: yuji9511 ***/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using lpair = pair<ll, ll>;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i=(m);i<(n);i++)
#define rrep(i,m,n) for(ll i=(m);i>=(n);i--)
#define printa(x,n) for(ll i=0;i<n;i++){cout<<(x[i])<<" \n"[i==n-1];};
void print() {}
template <class H,class... T>
void print(H&& h, T&&... t){cout<<h<<" \n"[sizeof...(t)==0];print(forward<T>(t)...);}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll L,R,M,K;
    cin >> L >> R >> M >> K;
    ll al = L % M, ar = R % M;
    if(R - L + 1 >= M){
        print("Yes");
    }else if(al > ar){
        print("Yes");
    }else if(K == 0){
        print("Yes");
    }else if(al == 0){
        print("Yes");
    }else{
        ll lv = L * K;
        ll rv = R * K;
        if(rv - lv + 1 >= M){
            print("Yes");
        }else if(lv % M == 0){
            print("Yes");
        }else if(lv % M > rv % M){
            print("Yes");
        }else{
            print("No");
        }
    }




    

}