#include  <bits/stdc++.h>
using namespace std;
static int fast_io = []() { std::ios::sync_with_stdio(false); cin.tie(nullptr); return 0; }();
int main(){
  int s,w;
  cin>>s>>w;
  if(w>=s){
    cout<<"unsafe"<<"\n";  
  }
  else{
    cout<<"safe"<<"\n";  
  }
  return 0;
}