#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define MAX_C 1000000001
#define MOD 1000000007

int main() {
  int s, w;
  cin >> s >> w;

  cout << ((s <= w) ? "unsafe" : "safe") << endl;
}
