#include <iostream>
#include<cmath>
using namespace std;
class Date {
	int year, month, day;
	public:
		Date() {}
		Date(int a, int b, int c) : year(a), month(b), day(c) {}
		Date operator + (const Date &a) {Date c(this -> year + a.year , this -> month + a.month ,this -> day + a.day ); c.norm(); return c; }
		Date operator + (const int &a) {Date c(this -> year, this -> month, this -> day + a); c.norm(); return c; }
		Date operator - (const Date &a) {Date c(this -> year - a.year , this -> month - a.month ,this -> day - a.day ); c.norm(); return c; }
		friend Date operator ++ (Date &a);
		friend Date operator ++ (Date &a, int);
		Date & operator = (const Date &a) {
			year = a.year;
			month = a.month;
			day = a.day;
			return *this;
		}
		Date & operator = (const int a) {
			year = month = day = a;
			return *this;
		}
		void set(char k) {
			cout << "Please, enter YYYY MM DD  " << k << ": ";
			cin >> year >> month >> day;
			return;
		}
		void get(char k) {
			cout << " Date " << k << ": " << year << " " << month << " " << day << endl;
			return;
		}
		int getMaxDay(int month, int year) {
			if (month == 2) {
				if (isLeapYear(year)) {
					return 29;
				}
				return 28;
			}
			if (month % 2 == 0) {
				if (month < 7) return 30;
				return 31;
			}
			if (month < 8) return 31;
			return 30;
		}
		bool isLeapYear(int year) {
			return (!(year % 4) && year % 100 || !(year % 400));
		}
		void norm() {
			if (day < 1) {
				day += getMaxDay(month - 1, year);
				month--;
			}
			if (month < 1) {
				year--;
				month += 12;
			}
			if (day > getMaxDay(month, year)) {
				day -= getMaxDay(month, year);
				month++;
			}
			if (month > 12) {
				month -= 12;
				year++;
			}
			return;
		}
};

int main() {

	Date a, b, c;

	a.set('a');
	b.set('b');

	cout << endl <<  " operator + " << endl;
	c = a + b;
	cout << "c = a + b" << endl;
	c.get('c');

	c = a + 30;
	cout << "c = a + 30" << endl;
	c.get('c');

	cout << endl << " operator - " << endl;
	c = a - b;
	cout << "c = a - b" << endl;
	c.get('c');

	cout << endl << " operator ++ " << endl;
	c = ++a;
	cout << "c = ++a " << endl;
	c.get('c');
	a.get('a');

	c = a++;
	cout << "c = a++ " << endl;
	c.get('c');
	a.get('a');

	return 0;
}

Date operator ++ (Date &a) {
	a.day = a.day + 1;
	a.norm();
	return a;
}
Date operator ++ (Date &a, int){
	Date _a = a;
	a.day = a.day + 1;
	a.norm();
	return _a;
}