#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;


int main() {
  int s, w;
  cin >> s >> w;
  if (s <= w) cout << "unsafe" << endl;
  else cout << "safe" << endl;
  return 0;
}