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

#define rng(i, a, b) for(int i = int(a); i < int(b); i++)
#define rep(i, b) rng(i, 0, b)
#define pb push_back
#define eb emplace_back
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed

int main() {
  int n, a, b, ans = 0;
  //string s;
  cin >> a >> b;
  //vector<int> v(n), c(n);
  //if(1) {}
  //for(int i = 0; i < n; i++){}
  cout << ((a > b)? "safe" : "unsafe") << endl;
}