#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG

using namespace std;
typedef long long ll;

#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define REP(a, b, m) for (ll a = (ll)(b); a < (ll)(m); a++)

int main()
{
    int n,m;
    cin >> n>>m;
    if (n<=m) {
        cout << "unsafe" << endl;
    }else {
        cout << "safe" << endl;
    }
}