#include <iostream>
using namespace std;
int main(void){
    int A, B, C;
    cin >> A >> B >> C;
    if (A*A + B*B < C*C){
        cout << "Yes" << endl;
    }
    else{
        cout << "No" << endl;
    }
    
}

#include "bits/stdc++.h"
#define rep(i,n) for(int i = 0; i < (n); ++i)
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int v, t, s, d;
	cin >> v >> t >> s >> d;
	if(v*t <= d && d <= v*s) cout << "No" << endl;
	else cout << "Yes" << endl;
	return 0;
}