//#include <bits/stdc++.h>
#include <iostream>
#include <string>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define MOD 1000000007
#define PI 3.1415926535

int main(void){

    int s, w;
    cin >> s >> w;
    if(s<=w)
        cout << "unsafe" << endl;
    else
        cout << "safe" << endl;

    return 0;
}
