#include <iostream>

using namespace std;
typedef long long ll;

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