ыыыы

#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include <bitset>
#include <iomanip>
#include <math.h>
#include <stdlib.h>
#include <map>
#include <unordered_map>
#include <tuple>
#include <cmath>
#include <functional>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <deque>
#include <numeric>
#include <cstring>


struct v {
    int l;
    int r;
    std::string name;
    int type;
};


const std::vector<int> def_year = {30, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
const std::vector<int> spc_year = {30, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
std::vector<v> events;


bool cmp(const v& v1, const v& v2) {
    if (v1.l < v2.l)
        return true;
    else if (v1.l == v2.l && v1.r < v2.r)
        return  true;
    else if (v1.l == v2.l && v1.r == v2.r && v1.type > v2.type)
        return true;
    else
        return false;
}


bool operator<(const v& v1, const v& v2) {
    return cmp(v1, v2);
}


int date_to_num(std::string s) {
    int days = (s[0] - 48) * 10 + (s[1] - 48);
    int months = (s[3] - 48) * 10 + (s[4] - 48);
    int years = (s[6] - 48) * 1000 + (s[7] - 48) * 100 + (s[8] - 48) * 10 + (s[9] - 48);
    int number = 0;
    int cur_year = 1500;
    while (cur_year < years) {
        if ((cur_year % 4 == 0 && cur_year % 100 != 0) || cur_year % 400 == 0)
            number += 366;
        else
            number += 365;
        cur_year++;
    }
    if ((cur_year % 4 == 0 && cur_year % 100 != 0) || cur_year % 400 == 0) {
        for (int i = 0; i < months - 1; i++)
            number += spc_year[i];
    } else {
        for (int i = 0; i < months - 1; i++)
            number += def_year[i];
    }
    number += days;
    return number;
}


void num_to_date(int number) {
    int year = 1500;
    int months = 1;
    while (true) {
        if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
            if (number > 366)
                number -= 366;
            else
                break;
        else
            if (number > 365)
                number -= 365;
            else
                break;
        year++;
    }
    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
        for (int i = 0; i < 12; i++) {
            if (number > spc_year[i])
                months++;
            else
                break;
        }
    else
        for (int i = 0; i < 12; i++) {
            if (number > def_year[i]) {
                months++;
                number -= def_year[i];
            } else
                break;
        }
    int days = number + 1;
    if (days < 10)
        std::cout << '0' << days << '.';
    else
        std::cout << days << '.';
    if (months < 10)
        std::cout << '0' << months << '.';
    else
        std::cout << months << '.';
    std::cout << year;
}


bool check(int M, int n) {
    std::unordered_set<std::string> names;
    int i = M;
    int j = 0;
    std::set<v> queue;
    while (j < events.size()) {
        while (j < events.size() && events[j].l <= i) {
            if (events[j].type == 0)
                queue.insert(events[j]);
            else if (events[j].type == 1)
                if (names.find(events[j].name) == names.end())
                    return false;
            j++;
        }
        if (queue.size() != 0) {
            names.insert((*queue.begin()).name);
            queue.erase(*queue.begin());
        }
        i++;
    }
    return true;
}


int main() {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    std::cout.tie(0);
    int n;
    std::cin >> n;
    std::string name, date;
    int t;
    int min_L = (int) 1e9, min_R = (int) 1e9;
    for (int i = 0; i < n; i++) {
        std::cin >> name >> date >> t;
        int num = date_to_num(date);
        events.push_back({num - t, num, name, 0});
        events.push_back({num, num - t, name, 1});
        min_L = std::min(min_L, num - t);
        min_R = std::min(min_R, num - 1);
    }
    std::sort(events.begin(), events.end(), cmp);
    int L = min_L, R = min_R;
    while (R - L > 1) {
        int M = (L + R) / 2;
        if (check(M, n))
            L = M;
        else
            R = M;
    }
    if (check(L, n)) {
        //std::cout << L << '\n';
        num_to_date(L);
    } else
        std::cout << "Impossible";
    return 0;
}