#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
const long long INF = 9999999999999999;
using ll = long long;
int main(){
  int A,B;
  cin>>A>>B;
  if(A<=B){
    cout << "unsafe" << endl;
  }
  else{
    cout << "safe" << endl;
  }
  return 0;
}
