#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ii = pair<int, int>;

const int MAX { 200010 };
const ll MOD { 1000000007 }, oo { 1LL << 62 };

int solve(int N, const vector<int>& xs)
{
    return 0;
}

int main()
{
    ios::sync_with_stdio(false);

    int S, W;
    cin >> S >> W;

    cout << (W >= S ? "unsafe" : "safe") << '\n';

    return 0;
}
