BR012daysInMonth

#include <iostream>

//month#    1   2   3   4   5   6   7           #   8   9   10  11  12
//days      31  28  31  30  31  30  31          #   31  30  31  30  31
//          (month < 8) and (month % 2 != 0)    # (month >= 8) and (month % 2 == 0)
//          ((month < 8) and (month % 2 != 0)) or ((month >= 8) and (month % 2 == 0))
int main()
{
    int days{ 30 };
    int month{ 2 };
    int year{ 2021 };

    std::cout << "Enter year:\n";
    std::cin >> year;
    std::cout << "Enter month 1-12:\n";
    std::cin >> month;

    const bool isLeap{ (year % 400 == 0) or (year % 4 == 0) and (year % 100 != 0) };

    days += ((month < 8) and (month % 2 != 0) or (month >= 8) and (month % 2 == 0)) + (-2 * (month == 2) + isLeap);

    std::cout << "In month# " << month << " there are " << days << " days\n";
    return 0;
}