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

int main(void)
{
  ios_base::sync_with_stdio(false);
  cin.tie(0); cout.tie(0);

  int S, W; cin >> S >> W;

  if (S <= W)
    cout << "unsafe" << endl;
  else
    cout << "safe" << endl;

  return 0;
}
