#include <bits/stdc++.h>
using namespace std;
#define mod 1e9+7
typedef long long ll; 
typedef vector<long long> vi; 
typedef pair<int, int> ii; 
typedef vector<ii> vii; 
typedef set<int> si; 
typedef map<string, int> msi; 

int main(){
  ios_base::sync_with_stdio(false); 
    cin.tie(NULL);
    ll t,n;
   cin>>t>>n;
  if(n>=t) cout<<"unsafe\n";
  else cout<<"safe\n";
  return 0;}