//
//  main.cpp
//  ABC164
//
//  Created by 安藤光希 on 2020/04/26.
//  Copyright © 2020 安藤光希. All rights reserved.
//

#include <bits/stdc++.h>
#include <iostream>
#include <math.h>
#define rep(i, n) for (int i = 0; i<n; i++)
using namespace std;
// https://atcoder.jp/contests/abc163/tasks/abc163_c
typedef long long ll;


int main() {
    ll S, W;
    cin >> S >> W;
    
    if (S > W) cout << "safe" << endl;
    else cout << "unsafe" << endl;

}
