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

using i64 = int_fast64_t;
using f64 = double;

constexpr i64 INF = INT_FAST64_MAX / 2;
constexpr f64 EPS = DBL_EPSILON;

void solve() {
    i64 s, w;
    cin >> s >> w;
    cout << (s <= w ? "unsafe" : "safe") << endl;
}

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    solve();
}
