#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;
typedef long double ld;

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	ll l, r, m, k;
	cin >> l >> r >> m >> k;

	ll lm = l % m, rm = r % m;
	if(k == 0 || lm == 0 || rm == 0){
		cout << "Yes" << endl;
		exit(0);
	}

	if(lm + (r - l) >= m){
		cout << "Yes" << endl;
		exit(0);
	}
	
	ll lmk = lm * k, rmk = rm * k;
	if(lmk % m + (rmk - lmk) >= m){
		cout << "Yes" << endl;
	}else{
		cout << "No" << endl;
	}
}