#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
typedef long long ll;
ll mod_pow(ll, ll, ll);
ll mod_fact(ll, ll);
ll mod_inv(ll, ll);
//
int main(){
    int a, b;
    cin >> a >> b;
    if(a > b) cout << "safe";
    else cout << "unsafe";
}