Problem:
Score: 300 points

Problem Statement

In Republic of Atcoder, there are N prefectures, and a total of M cities that belong to those prefectures.

City i is established in year Y_i and belongs to Prefecture P_i.

You can assume that there are no multiple cities that are established in the same year.

It is decided to allocate a 12-digit ID number to each city.

If City i is the x-th established city among the cities that belong to Prefecture i, the first six digits of the ID number of City i is P_i, and the last six digits of the ID number is x.

Here, if P_i or x (or both) has less than six digits, zeros are added to the left until it has six digits.

Find the ID numbers for all the cities.

Note that there can be a prefecture with no cities.

Constraints

1 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq P_i \leq N

1 \leq Y_i \leq 10^9

Y_i are all different.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
P_1 Y_1
:
P_M Y_M

Output

Print the ID numbers for all the cities, in ascending order of indices (City 1, City 2, ...).

Sample Input 1

2 3
1 32
2 63
1 12

Sample Output 1

000001000002
000002000001
000001000001

As City 1 is the second established city among the cities that belong to Prefecture 1, its ID number is 000001000002.

As City 2 is the first established city among the cities that belong to Prefecture 2, its ID number is 000002000001.

As City 3 is the first established city among the cities that belong to Prefecture 1, its ID number is 000001000001.

Sample Input 2

2 3
2 55
2 77
2 99

Sample Output 2

000002000001
000002000002
000002000003

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long ll;
long long MOD = 1e9 + 7;
using namespace std;

int main() {
  int N, M;
  cin >> N >> M;
  vector<int> P(100001);
  vector<int> Y(100001);
  vector<vector<int>> y_sort(100001);

  rep(i, M) {
    cin >> P[i] >> Y[i];
    y_sort[P[i]].push_back(Y[i]);
  }

  rep(i, N) { sort(y_sort[P[i + 1]].begin(), y_sort[P[i + 1]].end()); }

  for (int i = 0; i < M; i++) {
    auto iter = lower_bound(y_sort[P[i]].begin(), y_sort[P[i]].end(), Y[i]);
    int order = iter - y_sort[P[i]].begin();
    cout.fill('0');
    cout << setw(6) << P[i] << setw(6) << order + 1 << endl;
  }

  return 0;
}