bool isless_m( string str1,  string str2) {
    int N = min(str1.size(), str2.size());
    for (int i = 0; i < N; ++i) {
        if (str1[i] < str2[i]) {
            return true;
        }
        else if (str1[i] > str2[i]) {
            return false;
        }
    }
    return false;
}

void noPrefix(vector<string> words) {
       
    if (words.size() == 1) {
        cout << "GOOD SET\n";
        return;
    }    

    set<string,decltype(&isless_m)> mp(&isless_m);

    for (int i = 0; i < words.size(); ++i) {
        auto it=mp.insert(words[i]);
        if (!it.second) {
             cout << "BAD SET\n";            
            cout << words[i]<<"\n";
            return;
        }
    }
    cout << "GOOD SET\n";
   
}