#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i < (n); i++)
#define erep(i, n) for (int i = 0; i <= (n); i++)
#define erep1(i, n) for (int i = 1; i <= (n); i++)
using namespace std;
using ll = long long;


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