#!/usr/bin/env python3

def is_leap_year(year: int):
    return year % 4 == 0 and year % 100 != 0 or year % 400 == 0


def get_day_of_month(year, month: int) -> int:
    match month:
        case 1 | 3 | 5 | 7 | 8 | 10 | 12:
            return 31
        case 4 | 6 | 9 | 11:
            return 30
        case 2 if is_leap_year(year):
            return 29
        case 2:
            return 28
        case _:
            raise Exception(f"invalid month: {month}")


def get_day_of_month2(year, month: int) -> int:
    if month in {1, 3, 5, 7, 8, 10, 12}:
        return 31
    elif month in {4, 6, 9, 11}:
        return 30
    elif month == 2 and is_leap_year(year):
        return 29
    elif month == 2:
        return 28
    else:
        raise Exception(f"invalid month: {month}")


if __name__ == "__main__":
    print(1582, is_leap_year(1582))
    print(2000, is_leap_year(2000))
    print(2100, is_leap_year(2100))

    print(2000, 1, '->', get_day_of_month(2000, 1), get_day_of_month2(2000, 1))
    print(2000, 2, '->', get_day_of_month(2000, 2), get_day_of_month2(2000, 2))
    print(2001, 2, '->', get_day_of_month(2001, 2), get_day_of_month2(2001, 2))