#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;

int main(){
    ll L,R,M,K;
    cin >> L >> R >> M >> K;
    if(K==0 || L%M > R%M || L+M-1 <= R || L%M ==0||R%M ==0){
        cout << "Yes" << endl;
        return 0;
    }
    L *= K;
    R *= K;
    if(L%M > R%M || L+M-1 <= R || L%M ==0||R%M ==0){
        cout << "Yes" << endl;
    }else{
        cout << "No" << endl;
    }

    return 0;
}