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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
$all = [];
$line1 = fgets(STDIN);
$i = 0;
while (!feof(STDIN)) {
    $line = fgets(STDIN);
    $arr = explode(' ', $line);
    $all[] = ['p' => $arr[0], 'y' => $arr[1], 'i' => ++$i];
}
foreach ($all as $key => $row) {
    $p[$key] = $row['p'];
    $y[$key] = $row['y'];
    $i_tmp[$key] = $row['i'];
}
array_multisort($p, SORT_ASC, $y, SORT_ASC, $all);
$new = [];
$y_num = 0;
$p_mem = 0;
foreach ($all as $key => $row) {
    if ($p_mem != $row['p']) {
        $y_num = 0;
        $p_mem = $row['p'];
    }
    $new[$row['i']] = sprintf('%06d', $row['p']) . sprintf('%06d', ++$y_num);
}
ksort($new);
foreach ($new as $row) {
    echo $row . PHP_EOL;
}