data time

#include<iostream>
using namespace std;
class Time
{
	protected:
		int hour;
		int minute;
		int second;
	public:
		Time(int h = 0, int m = 0, int s = 0)
			:hour(h), minute(m), second(s){
				int s1 = second / 60;
				second = second % 60;
				minute = minute + s1;
				int m1 = minute / 60;
				minute = minute % 60;
				hour = hour + m1;
				hour = hour % 24;
			}
		Time(const Time &t)
  			:hour(t.hour), minute(t.minute), second(t.second){}
  		friend ostream& operator << (ostream &output,const Time &t);
  		friend istream& operator >> (istream &input, Time &t);
};

class Date
{
	protected:
		int year;
		int month;
		int day;
	public:
		Date(int y = 0, int m = 0, int d = 0)
			:year(y), month(m), day(d){}
		friend ostream& operator << (ostream &output, const Date &d);
		friend istream& operator >> (istream &input, Date &d);
};

class DateTime : public Date, public Time
{
	public:
		DateTime(int y = 0, int m = 0, int d = 0, int h = 0, int mi = 0, int s = 0)
  			:Date(y, m, d), Time(h, mi, s){}
		friend ostream& operator << (ostream &output, const DateTime &d);
  		friend istream& operator >> (istream &input, DateTime &d);
  		DateTime operator + (const DateTime &d);
  		DateTime operator - (const DateTime &d);
};

ostream& operator << (ostream &output,const Time &t)
{
	output << t.hour <<" h " << t.minute << " m " << t.second << " s";
	return output;
}

istream& operator >> (istream &input, Time &t)
{
	input >> t.hour >> t.minute >> t.second;
	if(t.hour < 0) t.hour = 24 - (-t.hour % 24);
	if(t.minute < 0) t.minute = 60 - (-t.minute % 60);
	if(t.second < 0) t.second = 60 - (-t.second % 60);
	int s1 = t.second / 60;
	t.second = t.second % 60;
	t.minute = t.minute + s1;
	int m1 = t.minute / 60;
	t.minute = t.minute % 60;
	t.hour = t.hour + m1;
	t.hour = t.hour % 24;
	return input;
}

ostream& operator << (ostream &output, const Date &d)
{
	output << d.year << " year " << d.month << " month " << d.day << " day";
	return output; 
}

istream& operator >> (istream &input, Date &d)
{
	cin >> d.year >> d.month >> d.day;
	return input;
}

ostream& operator << (ostream &output, const DateTime &d)
{
	output << (Date) d << " ";
	output << (Time) d;
	return output;
}

istream& operator >> (istream &input, DateTime &d)
{
	input >> d.year >> d.month >> d.day >> d.hour >> d.minute >> d.second;
	return input;
}

DateTime DateTime::operator - (const DateTime &d)
{
	return DateTime(year - d.year, month - d.month, day - d.day,hour - d.hour, minute - d.minute, second - d.second);
}

int main(int argc, char const *argv[])
{
	DateTime a(2014,2, 2, 11, 22, 12);
	DateTime b(2015, 5, 6, 17, 27, 30);
	cout << "DateTime a = " << a << endl;
	cin >> a;
	cout << "DateTime a = " << a << endl;
	cout << "DateTime b = " << b << endl;
	cout << "b - a = " << b - a << endl;
	return 0;
}