#include <iostream>
using namespace std;

bool is_leap_year(const int year);
int days_in_month(const bool is_leap_year, const int month);
void print_calender(int month);

int main()
{
  int year = 0;
  int day = 0;
  bool day_valid = false;

  while (!year)
  {
    cout << "Enter the year: ";
    cin >> year;
    if (year < 0 || year > 9999)
    {
      cout << "That's not a valid year!" << endl;
      year = 0;
    }
  }

  while (!day_valid)
  {
    cout << "Enter the day of the week of January 1st, using 0 through 6." << endl;
    cout << "(0 = Sun, 1 = Mon, 2 = Tue, 3 = Wed, 4 = Thu, 5 Fri, 6 = Sat)" << endl;
    cin >> day;

    if (day < 0 || day > 6)
    {
      cout << "That's not a valid day! Must be between 0 and 6!" << endl;
    }
    else
    {
      day_valid = true;
    }
  }

  bool leap_year = is_leap_year(year);

  if (leap_year)
  {
    cout << year << " is a leap year." << endl;
    cout << "There are 29 days in February." << endl;
  }
  else
  {
    cout << year << " is not a leap year." << endl;
    cout << "There are 28 days in February." << endl;
  }

  int month = 0;
  while (!month)
  {
    cout << "Enter the month: ";
    cin >> month;

    if (month < 0 || month > 11)
    {
      cout << "That's not a valid month!" << endl;
      month = 0;
    }
  }
  cout << "There are " << days_in_month(leap_year, month) << " days in that month!" << endl;
}

bool is_leap_year(const int year)
{
  if (year % 4 == 0)
  {
    if (year % 100 == 0 && year % 400 != 0)
      return false;
    return true;
  }
  return false;
}

int days_in_month(const bool is_leap_year, const int month)
{
  int days_count = 0;

  switch (month)
  {
  case 8: case 3: case 5: case 10:
    days_count = 30;
    break;

  case 1:
    if (is_leap_year)
    {
      days_count = 29;
    }
    else
    {
      days_count = 28;
    }
    break;

  default:
    days_count = 31;
  }
  return days_count;
}

void print_calender(int month)
{
  for (int month = 0; month < 12; ++month)
  {
    switch (month)
    {
    case 0:
      return "January";
    case 1:
      return "February";
    case 2:
      return "March";
    case 3:
      return "April";
    case 4:
      return "May";
    case 5:
      return "June";
    case 6:
      return "July";
    case 7:
      return "August";
    case 8:
      return "September";
    case 9:
      return "October";
    case 10:
      return "November";
    case 11:
      return "December";
    }
  }
}