void find (string s , int k, vector <string> &res)
{
    string word= "";

    map < char , int > frq;
    map <string,bool> unq;
    int u = 0;
    int write = 0;
    for (int i = 0 ;i < s.size(); i ++)
    {
        char c = s[i];
        if (frq[c]==0)
            u++;
        frq[c]++;
        if (write < k)
            word+=c, write++;
        if (write == k)
        {
            if (u==k)
            {
                if (unq.find(word)== unq.end())
                res.push_back(word);
                unq[word]= true;
            }
            frq[word[0]]--;
            if (frq[word[0]] == 0)
                u--;
            word = word.substr(1,k-1);
            write--;

        }

    }
}

int main() {
    vector <string> res;
    vector <string> acc = {"wagl", "aglk", "glkn", "lkna", "knag", "gawu", "awun", "wuna", "unag", "nagw", "agwk", "kwag"};

    find("awaglknagawunagwkwagl",4,res);

    for (string x : res)
        cout<<x<< " ";
    cout<<endl;
      for (string x : acc)
        cout<<x<< " ";

}