#include <iostream>
#include <algorithm>
#include <iomanip>
using namespace std;
string alphabet = "abcdefghijklmnopqrstuvwxyz";
string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

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

