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
$input = trim(fgets(STDIN));
list($n, $m) = explode(' ', $input);

$inputs = [];
$count=0;
while($count <= $m) {
    $input = trim(fgets(STDIN));
    list($p, $y) = explode(' ', $input);
    $inputs[$p][$y] = $count;

    $count++;
}

$results = [];
foreach($inputs as $p => $input) {
    ksort($input);
    $cities = array_values($input);

    $id = 1;
    foreach($cities as $i => $count) {
        $results[$count]['p'] = $p;
        $results[$count]['c'] = $id;
        $id++;
    }
}

ksort($results);
foreach($results as $result) {
    echo str_pad((string)$result['p'], 6, "0", STR_PAD_LEFT)
        . str_pad((string)$result['c'], 6, "0", STR_PAD_LEFT)
        . "\n";
}