#include <iostream>
using namespace std;
#define STRMAX 101

int main()
{
    int V, T, S, D;
    char str[STRMAX];
    cin >> V >> T >> S >> D;
    int x_T = V * T;
    int x_S = V * S;
    if(D >= x_T && D <= x_S) cout << "No" << endl;
    else cout << "Yes" << endl;
    return 0;
}
#include<bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;
    int ans = n*1.08;
    if(206>ans){
        cout << "Yay!" << endl;
    }
    else if(206 == ans){
        cout << "so-so" << endl;
    }
    else{
        cout << ":(" << endl;
    }
}