struct TimePeriod
{
    int start;
    int end;
};

vector<TimePeriod> GetDiff(TimePeriod t, TimePeriod s)
{
    vector<TimePeriod> v;

    // partially overlapping - left side remains
    if (t.start < s.start && t.end <= s.end)
    {
        v.push_back(TimePeriod(t.start, s.start));
    }

    // partially overlapping - right side remains
    if (s.start <= t.start && s.end < t.end)
    {
        v.push_back(TimePeriod(s.end, t.end));
    }

    // TimePeriod s is contained in t
    if (t.start < s.start && s.end < t.end)
    {
        v.push_back(TimePeriod(t.start, s.start));
        v.push_back(TimePeriod(s.end, t.end));
    }

    // non-overlapping ranges & fully overlapping results in empty TimePeriod

    return v;
}