#include<bits/stdc++.h>
#define ll long long 
#define rep(i,n) for(ll i=0;i<n;i++)
using namespace std;
signed main(){
  ll a,b;
  cin>>a>>b;
  if(b>=a){
    cout<<"unsafe\n";
  }else{
    cout<<"safe\n";
  }
  return 0;
}