#include <iostream>
#include <string>
#include <vector>
#include <stdexcept>

using namespace std;

bool leapYear(int year) {
    return (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0));
}

class Date {
private:
    static constexpr int dayMonths[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
    int year, month, day;
public:
    Date() :year(-1), month(-1), day(-1) {}
    Date(int year, int month, int day) :year(year), month(month), day(day) {}

    friend Date& operator ++(Date& d);
    friend Date operator ++(Date& d, int);

    friend ostream& operator <<(ostream& out, Date& d);
};

Date& operator ++(Date& d) {
    d.day++;
    if (d.day == d.dayMonths[d.month - 1] + 1 + (d.month == 2 && leapYear(d.year))) {
        d.day = 1;
        d.month++;
        if (d.month == 13) {
            d.month = 1;
            d.year++;
        }
    }
    return d;
}

Date operator ++(Date& d, int) {
    Date old = d;
    ++d;
    return old;
}

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

int main() {
    Date d(2019, 12, 30);
    cout << d;
    Date d1 = d++;
    cout << d1 << d;
    ++d;
    cout << d;
}