#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
 
using namespace std;
using namespace __gnu_pbds;
 
#define debug(s) cerr << #s << " = " << s << '\n'
#define all(v) (v).begin(), (v).end()
#define mem(a,val) memset(a, val, sizeof a)
 
#define maxn 100010
#define INF 1e15
#define eps 1e-9
#define pi acos(-1.0)
#define ff first
#define ss second
#define endl '\n'
typedef long long ll;
 
//typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int a, b;
  cin >> a >> b;
  if (a >= b) cout << "unsafe" << endl;
  else cout << "safe" << endl;
}