#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define int long long int
#define mod 998244353
#define string_mod 2549536629329_base_255
#define pb push_back
#define F first
#define S second
#define ff first
#define endl "\n"
#define ss second
#define all(v) v.begin(), v.end()
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int power(int x, unsigned int y, int p)
{
  int res = 1;
  x = x % p;
  while (y > 0)
  {
    if (y & 1)
      res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res % p;
}
 
int32_t main()
{
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  
  int tc;
  tc = 1;
  //cin >> tc;
  while (tc--)
  {
    int s, w;
    cin >> s >> w;
    if(s<w){
      cout << "safe" << endl;
    }
    else{
      cout << "unsafe" << endl;
    }
  }

  return 0;
}