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 PHP (7.4.4) (judge verdict: Accepted)

<?php
  list($n,$m) = explode(" ", trim(fgets(STDIN)));
  $city = [];
  $p = [];
  $y = [];
  for ($i=0; $i<$m; $i++) {
    list($p[$i],$y[$i]) = explode(" ", trim(fgets(STDIN)));    
    $city[$y[$i]]=$p[$i];
  }
  ksort($city);
  $pref=[];
  $prefcnt=[];
  foreach($city as $key => $val){
    if(!isset($pref[$val])) {
      $pref[$val] = [];
      $prefcnt[$val] = 0;
    }
    $prefcnt[$val]++;
    $pref[$val][$key]=$prefcnt[$val];
  }

  for ($i=0; $i<$m; $i++) {
    echo str_pad($p[$i],6,"0",STR_PAD_LEFT);
    echo str_pad($pref[$p[$i]][$y[$i]],6,"0",STR_PAD_LEFT);
    echo PHP_EOL;
  }