comparator example

{
    if (a.year != b.year) {
        return a.year < b.year;
    }
    if (a.month != b.month) {
        return a.month < b.month;
    }
    if (a.date != b.date) {
        return a.date < b.date;
    }
    if (a.surname != b.surname) {
        return a.surname < b.surname;
    }
    return a.name < b.name;
}