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

typedef long long ll;
typedef long double ld;

int main(){
    ios_base::sync_with_stdio(false), cin.tie(0);
    cout.precision(10);
    cout << fixed;

    int a, b;
    cin >> a >> b;
    if(a > b) cout << "safe";
    else cout << "unsafe";
    return 0;
}
