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

// START
list($n, $m) = Util::input(1);
$cityMap = [];
$inputList = [];
for ($i = 0; $i < $m; ++$i) {
    list($p, $y) = Util::input(1);
    $inputList[] = $p . '_' . $y;
    if (empty($cityMap[$p])) {
        $cityMap[$p] = [];
    }
    $cityMap[$p][$y]= 1;
}
foreach ($cityMap as $key => $m) {
    ksort($cityMap[$key]);
    $c = 1;
    foreach ($cityMap[$key] as $k => $v) {
        $cityMap[$key][$k] = $c;
        $c += 1;
    }
}

foreach ($inputList as $input) {
    list($p, $y) = explode('_', $input);
    echo sprintf("%06d%06d", $p, $cityMap[$p][$y]) . PHP_EOL;
}
class Util
{
    public static function input($isSplitSpace = false)
    {
        $input = trim(fgets(STDIN));
        if (!$isSplitSpace) {
            return $input;
        }

        return explode(' ', $input);
    }

    public static function arrToStr($arr)
    {
        return implode(",", $arr);
    }
}