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 Kotlin (1.0.0) (judge verdict: Accepted)

import java.lang.Long.parseLong
import java.util.*

fun main(args:Array<String>) {
    val mod = 1000000007L
    var (N,M) = readLine()!!.split(' ').map(String::toInt)

    val list = Array(N+1){ mutableListOf<Pair<Int, Long>>()}
    val ans = Array(M){""}
    for (m in 0 until M) {
        val (P, Y) = readLine()!!.split(' ').map(String::toLong)
        list[P.toInt()].add(m to Y)
    }
    for ((i0,l) in list.withIndex()) {
        l.sortBy { it.second }
        for ((i1, p) in l.withIndex())
            ans[p.first] = "%06d%06d".format(i0, i1+1)
    }

    println(ans.joinToString("\n"))
}