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

const ll BIG = 1e6 + 9 ;
ll tc , x , y , a , b ;

int main()
{
    int s , w ;
    cin >> s >> w ;
    cout << ( s <= w ? "unsafe" : "safe") ;
    return 0 ;

}


Measured memory_bytes: 3672