#include <bits/stdc++.h>
using namespace std;

#define lli long long int
#define pb push_back
#define in insert
#define pi pair<int, int>
#define pii pair<int, pi>
#define mp make_pair
#define fir first
#define sec second
#define MAXN 101
#define MAXS 901
#define INF 1000000000
#define mod 1000000007

signed main()
{
  int s, w;
  cin >> s >> w;
  (s <= w) ? cout << "unsafe\n" : cout << "safe\n";
  return 0;
}