#include<iostream>
#include<vector>
#include<set>
#include<queue>
#include<map>
#include<algorithm>
#include<cstring>
#include<string>
#include<cassert>
#include<cmath>
#include<climits>
#include<iomanip>
#include<stack>
#include<unordered_map>
#include<bitset>
#include<limits>
#include<array>
using namespace std;
#define MOD 1000000007
#define rep(i,m,n) for(int (i)=(int)(m);i<(int)(n);i++)
#define REP(i,n) rep(i,0,n)
#define ll long long
#define ull unsigned long long
#define all(hoge) (hoge).begin(),(hoge).end()

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

	ll l, r, m, k;
	cin >> l >> r >> m >> k;
	ll mn = l * k % m;
	ll dif = r - l;
	if ((m - mn) % m > dif* k)cout << "No" << "\n";
	else cout << "Yes" << "\n";

	return 0;
}