#include <iostream>
#include <cstdlib>

using namespace std;

class Birthday
{
public:
    // Constructors
    Birthday();
    Birthday(int y, int m, int d);

    int get_year() const;
    int get_month() const;
    int get_date() const;

    void set_year(int y);
    void set_month(int m);
    void set_date(int d);

    void print() const;

    friend bool equal(const Birthday& bd1, const Birthday& bd2);
    friend int years_apart(const Birthday& bd1, const Birthday& bd2);
    friend int operator -(const Birthday& bd1, const Birthday& bd2);
    friend ostream& operator <<(ostream& outs, const Birthday& bd);
    friend istream& operator >>(istream& ins, Birthday& bd);

private:
    int year, month, date;
};

Birthday::Birthday() : year(0), month(0), date(0)
{
    cout << "Default constructor called!" << endl;
}

Birthday::Birthday(int y, int m, int d) : year(y), month(m), date(d)
{
    // Empty body
}

int Birthday::get_year()  const { return year; }
int Birthday::get_month() const { return month; }
int Birthday::get_date()  const { return date; }

void Birthday::set_year(int y)  { year = y; }
void Birthday::set_month(int m) { month = m; }
void Birthday::set_date(int d)  { date = d; }

void Birthday::print() const
{
    cout << month << "/" << date << "/" << year << endl;
}

int main()
{
    Birthday bd1;              // call default constructor
    Birthday bd2(1990, 9, 2);  // call constructor
    Birthday bd3(2001, 5, 8);  // call constructor

    bd1.print();
    bd2.print();
    bd3.print();

    cout << years_apart(bd2, bd3) << endl;

    cout << bd2 - bd3 << endl;
    cout << bd1 << ", " << bd2 << ", " << bd3 << endl;

    cout << endl;
    cout << "Enter two birthdays: ";
    cin >> bd1 >> bd2;
    cout << bd1 << ", " << bd2 << endl;
}

bool equal(const Birthday& bd1, const Birthday& bd2)
{
    return    (bd1.year  == bd2.year)
           && (bd1.month == bd2.month)
           && (bd1.date  == bd2.date);
}

int years_apart(const Birthday& bd1, const Birthday& bd2)
{
    return abs(bd1.year - bd2.year);
}

int operator -(const Birthday& bd1, const Birthday& bd2)
{
    return abs(bd1.year - bd2.year);
}

ostream& operator <<(ostream& outs, const Birthday& bd)
{
    outs << bd.month << "/" << bd.date << "/" << bd.year;
    return outs;
}

istream& operator >>(istream& ins, Birthday& bd)
{
    int y, m, d;
    char ch;

    ins >> ch;
    if (ch == '{')
    {
        ins >> y;

        ins >> ch;
        if (ch == ',')
        {
            ins >> m;

            ins >> ch;
            if (ch == ',')
            {
                ins >> d;

                ins >> ch;
                if (ch == '}')
                {
                    bd.year  = y;
                    bd.month = m;
                    bd.date  = d;
                }
            }
        }
    }

    return ins;
}