#include <bits/stdc++.h>

using ll = long long;
using namespace std;
const int INFint = 2e9+1;
const ll INFll = 2e18+1;
ll MOD=1e9+7;


int main(){
  int s,w;
  cin>>s>>w;
  if(w >= s){
    cout << "unsafe" << endl;
  }else{
    cout << "safe" << endl;
  }
  return 0;
}

