Фигня

#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>


using namespace std;
int main() {
    int n;
    cin >> n;

    //year/month/day
    int year = 3, month, day;

    while (n > 0) {
        int y = min(year, 12);
        for (month = 2; month < y; month++) {
            int d = min(month, 11);
            for (day = 1; day < d; day++) {
                n -= 1;
                if (n <= 0) {
                    cout << year << "/" << month << "/" << day;
                    return 0;
                }
            }
        }
        year++;
    }
    cout << year << "/" << month << "/" << day;
    return 0;
}