#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;

int main() 
{ 
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll a, b;
    cin >> a >> b;
    if(a <= b) {
        cout << "unsafe\n";
    } else {
        cout << "safe\n";
    }
    return 0; 
}