for (auto it = m.begin(); it != m.end(); it++)
{
    for (list <int>::iterator it1 = it->second.begin(); it1 != it->second.end(); it1++)
    {
        start[c[*it1] - 'a'].push_back(*it1);
        if ((*it1) != n - 1)
            ending[c[(*it1) + 1] - 'a'].push_back(*it1);
    }
    for (int i = 0; i < 26; i++)
    {
        for (int j = 0; j < start[i].size(); j++)
        {
            vector <int>::iterator it = lower_bound(ending[i].begin(), ending[i].end(), start[i][j]);
            result += (ending[i].end() - it);
        }
        start[i].clear();
        ending[i].clear();
    }
}