#pragma comment(linker, "/STACK:1024000000,1024000000")

#include <cstdio>

#include <string>

#include <cstdlib>

#include <cmath>

#include <iostream>

#include <cstring>

#include <set>

#include <queue>

#include <algorithm>

#include <vector>

#include <map>

#include <cctype>

#include <cmath>

#include <stack>

#include <sstream>

#include <list>

#include <assert.h>

#include <bitset>

#include <numeric>

#define debug() puts("++++")

#define gcd(a, b) __gcd(a, b)

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define fi first

#define se second

#define pb push_back

#define sqr(x) ((x)*(x))

#define ms(a,b) memset(a, b, sizeof a)

#define sz size()

#define be begin()

#define ed end()

#define pu push_up

#define pd push_down

#define cl clear()

#define lowbit(x) -x&x

//#define all 1,n,1

#define FOR(i,n,x)  for(int i = (x); i < (n); ++i)

#define freopenr freopen("in.in", "r", stdin)

#define freopenw freopen("out.out", "w", stdout)

using namespace std;

typedef long long LL;

typedef unsigned long long ULL;

typedef pair<int, int> P;

const int INF = 0x3f3f3f3f;

const LL LNF = 1e17;

const double inf = 1e20;

const double PI = acos(-1.0);

const double eps = 1e-8;

const int maxn = 5e4 + 10;

const int maxm = 700 + 10;

const LL mod = 1000000007;

const int dr[] = {-1, 1, 0, 0, 1, 1, -1, -1};

const int dc[] = {0, 0, 1, -1, 1, -1, 1, -1};

const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};

int n, m;

const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

inline bool is_in(int r, int c) {

  return r >= 0 && r < n && c >= 0 && c < m;

}

inline int readInt(){ int x;  scanf("%d", &x);  return x; }

struct Node{

  int t, tim;

  bool operator < (const Node &p) const{

    return tim > p.tim || tim == p.tim && t < p.t;

  }

};

Node a[maxn];

char s[20];

int date;

bool is_leap_year(int n){

  if(n % 400 == 0)  return true;

  if(n % 100 == 0)  return false;

  if(n % 4 == 0)  return true;

  return false;

}

int cal(int y, int m, int d){

  int ans = date;

  for(int i = 1900; i < y; ++i)  ans += is_leap_year(i) ? 366 : 365;

  for(int i = 1; i < m; ++i)  ans += is_leap_year(y) ? monn[i] : mon[i];

  ans += d;

  return ans;

}

struct Sub{

  int t, tim;

  bool operator < (const Sub &p) const{

    return tim - t < p.tim - p.t;

  }

};

void print(int n){

  int y, m;

  for(int i = 0; ; ++i){

    int t = is_leap_year(i) ? 366 : 365;

    if(n > t)  n -= t;

    else{ y = i;  break; }

  }

  for(int i = 1; ; ++i){

    int t = is_leap_year(y) ? monn[i] : mon[i];

    if(n > t)  n -= t;

    else{ m = i;  break; }

  }

  printf("%02d.%02d.%04d\n", n, m, y);

}

int main(){

  date = 0;

  for(int i = 0; i < 1900; ++i)  date += is_leap_year(i) ? 366 : 365;

  while(scanf("%d", &n) == 1){

    for(int i = 0; i < n; ++i){

      scanf("%s", s);

      int y, m, d;scanf("%d.%d.%d", &d, &m, &y);

      scanf("%d", &a[i].t);

      a[i].tim = cal(y, m, d);

    }

    sort(a, a + n);

    priority_queue<Sub> pq;

    pq.push((Sub){a[0].t, a[0].tim});

    bool ok = true;

    int t = a[0].tim - 1;

    for(int i = 1; i < n && ok; ++i){

      int det = a[i-1].tim - a[i].tim - 1;

      while(det-- > 0){

        if(pq.empty())  break;

        Sub x = pq.top();  pq.pop();

        if(x.tim - x.t > t){

          ok = false;  break;

        }

        else  --t;

      }

      pq.push((Sub){a[i].t, a[i].tim});

      t = a[i].tim - 1;

    }

    while(!pq.empty()){

      Sub x = pq.top();  pq.pop();

      if(x.tim - x.t > t){

        ok = false;  break;

      }

      else  --t;

    }

    if(!ok)  puts("Impossible");

    else  print(t + 1);

  }

  return 0;

}