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: Accepted)

<?php

fscanf(STDIN, "%d %d", $n, $m);
$X = [];
$Y = [];
for ($i = 0; $i < $m; ++$i) {
    fscanf(STDIN, "%d %d", $p, $y);
    $X[] = [$p, $y];
    $Y[$p][] = $y;
}

foreach ($Y as $key => $arr) {
    sort($arr);
    $Y[$key] = $arr;
}

for ($i = 0; $i < $m; ++$i) {
    $p = $X[$i][0];
    $y = $X[$i][1];

    // この配列を2分探索して順位を求める。
    $ty = $Y[$p];

    $l = 0;
    $r = count($ty);
    while ($r - $l >= 1) {
        $mid = intdiv($l + $r, 2);
        if ($ty[$mid] >= $y) {
            $r = $mid;
        } else {
            $l = $mid + 1;
        }
    }

    echo sprintf("%06d%06d\n", $p, $r + 1);
}