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

int main(){
  int N,M,K;
  string S;
  
  cin>>N>>M ;
  if(N<=M)
  
  
  
  cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl;
}

//  cout<<"Yes"<<endl;
//  cout<<" No"<<endl;
//  cout<<" "<<endl;
//  if()  ;
