bool checkWord(string str)
{
    bool check = str.length() <= 20;
    for (int i = 0; i < str.length() && check; i++)
        if (!isalpha(str[i])) check = false;
    return check;
}

bool notHere(string temp, vector<string> words)
{
    bool check = true;
    for (int i = 0; i < words.size() && check; i++)
        if (temp == words[i]) check = false;
    return check;
}

int main()
{
    string temp;
    vector<string> words;
   ifstream file("words.txt");
   while (!file.eof())
   {
       file >> temp;
       if (checkWord(temp) && notHere(temp, words))
           words.push_back(temp);
       temp = "";
   }
   for (int i = 0; i < words.size(); i++)
       cout << words[i] << endl;
}