#include <iostream>
#include <iomanip>

using namespace std;

int daysOfMonth(int m, int y);
bool isLeap(int year);
bool validate(int m, int d, int y);

int main()
{
	int m, d, y;
	int daysUntil = 0;
	int daysOfCurrentMonth;
	
	cout << "Type in a month: ";
	cin >> m;
	cout << "Type in a day: ";
	cin >> d;
	cout << "Type in a year: ";
	cin >> y;
	
	if(!validate(m, d, y))
	{
		cout << "Invalid date" << endl;
		return -1;
	}
	
	if((m == 12) && (d < 25))
	{
		daysUntil = 25 - d;
	}
	else {
		daysOfCurrentMonth = daysOfMonth(m, y);
		daysUntil += daysOfCurrentMonth - d;
		if(m == 12)
		{
			m = 1;
			d = 1;
			y++;
		}
		else {
			m++;
			d = 1;
		}
		
		for(int i = m; i < 12; i++)
		{
			daysOfCurrentMonth = daysOfMonth(i, y);
			daysUntil += daysOfCurrentMonth;
		}
		daysUntil += 25;
	}
	   cout << "Days until Christmas: " << daysUntil;
	   cout << endl << endl;
	   cout << "Enter to continue...";
	   cin.ignore(256, '\n');
	   cin.get();
	   return 0;
}

int daysOfMonth(int m, int y)
{
	switch(m)
	{
		case 9:
		case 4:
		case 6:
		case 11:
			return 30;
		case 2:
			if(isLeap(y))
				return 29;
			return 28;
		default:
			return 31;

	}
}

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

bool validate(int m, int d, int y)
{
	int daysInThisMonth = daysOfMonth(m, y);
	
	if (d > daysInThisMonth) {
		return false;
	}
	if(m > 12)
		return false;
	return true;
}