#include <bits/stdc++.h>
using namespace std;
using UL = unsigned int;
using ULL = unsigned long long;
using LL = long long;
#define rep(i, n) for(UL i = 0; i < (n); i++)

struct Problem {

    void Solve() {
        UL S, W; cin >> S >> W;
        if (S <= W) cout << "unsafe";
        else cout << "safe";
        cout << endl;
    }
};
int main() {
    unique_ptr<Problem> p(new Problem());
    //cout << fixed << setprecision(10);
    p->Solve();
    return 0;
}
