#include <iostream>
#include <map>
#include <set>
#include <vector>
#include <algorithm>
#include <tuple>

using namespace std;

struct Date{
    int year;
    int month;
    int day;
};

class Database {
public:

        bool operator<(const Date& lhs, const Date& rhs) {
            return tie(lhs.year, lhs.month, lhs.day) < tie(rhs.year, rhs.month, rhs.day);
        }

        void Print() {
            vector<Date> Dates;
            for (auto item:Ivents) {
                Dates.push_back(item.first);
            }

        }

private:
    map<Date, set<string>> Ivents;
};

int main() {

    return 0;