#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	ll l, r, m, k; cin>>l>>r>>m>>k;
	if(k==0){
		cout<<"Yes"<<endl;
		return 0;
	}
	ll x=(m-l*k%m)%m;
	if(x<=(r-l)*k) cout<<"Yes"<<endl;
	else cout<<"No"<<endl;
	return 0;
}