C++

#include
using namespace std;


class Date{
public:
	Date(int,int,int);
	Date(int,int);
	Date(int);
	Date();
	void disPlay();
private:
	int month;
	int day;
	int year;
};

Date::Date(int m,int d,int y):month(m),day(d),year(y){}

Date::Date(int m,int d):month(m),day(d){
	year=2021;
}

Date::Date(int m):month(m){
	year=2021;
	day=1;
}

Date::Date(){
	year=2021;
	day=1;
	month=1;
}

void Date::disPlay(){
	cout<