string s1;
    cin >> s1;
    string kek;
    int h = 0;
    for (int i = 0; i < s1.size(); ++i)
        if (s1[i] == ':')
            break;
        else kek += s1[i];
    h = stoi(kek);

    string lol;
    int m = 0;
    for (int i = s1.size() - 1; i >= 0; --i)
        if (s1[i] == ':')
            break;
        else lol += s1[i];

    reverse(all(lol));
    m = stoi(lol);

    int h2 = 0, m2 = 0;
    string s2;
    cin >> s2;
    string kek2;
    for (int i = 0; i < s2.size(); ++i)
        if (s2[i] == ':')
            break;
        else kek2 += s2[i];
    h2 = stoi(kek2);

    string lol2;
    for (int i = s2.size() - 1; i >= 0; --i)
        if (s2[i] == ':')
            break;
        else lol2 += s2[i];

    reverse(all(lol2));
    m2 = stoi(lol2);

    //cout << h << " " << m << endl << h2 << " " << m2;
    h += (m + m2) / 60 ? 1 : 0;
    bool f = log10((m + m2) % 60) == 0;
    string loh = "";
    if (f)
        loh = '0';
    cout << (h + h2) % 24 << ":" << loh << (m + m2) % 60;