#include "bits/stdc++.h"
using namespace std;
#define watch(x) cout << (#x) << " is " << (x) << endl

int main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  
  int s,w;
  cin>>s>>w;

  if(w>=s)cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl;  
     
  return 0;
}
