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

int s, w;

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