#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const long long INF = 1LL << 60;
const int mod = 1e9 + 7;

int main()
{
    int s, w;
    cin >> s >> w;
    string ans;
    if (s <= w)
    {
        ans = "unsafe";
    }
    else
    {
        ans = "safe";
    }
    cout << ans << endl;
    return 0;
}