void printBT(string sp, string sn, int v)
    {
        string s;

        if (v < currentSize)
        {
            s = sp;
            if (sn == cr) s[s.length() - 2] = ' ';
            printBT(s + cp, cr, 2 * v + 2);

            s = s.substr(0, sp.length() - 2);

            cout << s << sn << table[v] << endl;

            s = sp;
            if (sn == cl) s[s.length() - 2] = ' ';
            printBT(s + cp, cl, 2 * v + 1);
        }
    }


    void display()                              //wyswietlanie kopca z podzialem na poziomy
    {   cr = cl = cp = "  ";
        cr[0] = 218; cr[1] = 196;
        cl[0] = 192; cl[1] = 196;
        cp[0] = 179;

        printBT("", "", 0);
    }