#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    // sum(X) == 0 mod M
    // L <= X_i <= R (i = 1 to K)
    ll L,R,M,K; cin >> L >> R >> M >> K;
    L *= K, R *= K;
    cout << ([&]() {
        if(L % M == 0) return true;
        if(R % M == 0) return true;
        if(L / M * M + M <= R) return true;
        if(L <= R / M * M) return true;
        return false;
    }() ? "Yes" : "No") << endl;
}