#include <iostream>
using namespace std;                                                                                                                                                                                                                            int main() {                                                                                                                int s, w;                                                                                                               cin >> s;                                                                                                               cin >> w;                                                                                                               if (s > w) cout << "safe";                                                                                              else cout << "unsafe";                                                                                              }   