#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
namespace mp = boost::multiprecision;
// mp::cpp_int
// mp::cpp_dec_float_100
#define rep(i,s,n) for(ll i = (s); i < (n); i++)
#define all(v) v.begin(), v.end()
#define allr(v) v.rbegin(), v.rend()



int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  ll s, w;
  cin >> w >> w;
  
  //vector<ll> a(n);  rep(i, 0, n) cin >> a[i];
  
 // cout <<  << "\n";
  
  cout << ( s <= w ?"unsafe" :"safe") << "\n";
  
  //cout << fixed << setprecision(15) << n << "\n";

}