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
fscanf(STDIN, "%d %d", $N, $M);
for ($i = 0; $i < $M; $i++) {
    fscanf(STDIN, "%d %d", $P, $Y);
    $X = sprintf("Z%06d%06d", $P, $Y);
    $arr[] = $X;
}
asort($arr);
$prev = 'Z000000000000';
$cnt = 0;
$ans = [];
foreach ($arr as $k => $v) {
    $p1 = substr($v, 1, 6);
    $prev_p1 = substr($prev, 1, 6);
    if ($p1 !== $prev_p1) {
        $cnt = 1;
    } else {
        $cnt++;
    }
    $ans[$k] = sprintf("%06d%06d", $p1, $cnt);
    $prev = $v;
}
ksort($ans);
echo implode(PHP_EOL, $ans);