#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define rep(i,n) for (int i=0;i < n; ++i)
using namespace std;
const int INF = 2147483647;
using ll = long long;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n,m;
    cin >> n >> m;
    if(n>m) cout << "safe" << endl;
    else cout << "unsafe" << endl;
    return 0;
}

