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: Wrong Answer)

import java.util.*
import java.io.*

val pw = PrintWriter(System.out)

fun main(args: Array<String>) {
  	class Scanner(stream: InputStream) {
        private val reader = BufferedInputStream(stream).bufferedReader()
        private var st: StringTokenizer? = null
        fun next(): String {
            while (!(st?.hasMoreTokens() ?: false)) st = StringTokenizer(reader.readLine())
            return st!!.nextToken()
        }
    }
    val sc = Scanner(System.`in`)
    val n = sc.next().toLong()//sc.nextLong()
    val m = sc.next().toLong()//sc.nextLong()
    val py = mutableListOf<Pair<Long, Long>>()
    (0 until m).forEach {
        py.add(sc.next().toLong() to sc.next().toLong())
    }
    //println(problem113c(n, m, py))
  	problem113c(n, m, py)
}

fun problem113c(n: Long, m: Long, py: MutableList<Pair<Long, Long>>): String {
    var result = ""
    (0 until m.toInt()).forEach { i ->
        val number = py.filter { it.first == py[i].first }.sortedBy { it.second }.indexOf(py[i]) + 1
        //result += String.format("%06d", py[i].first) + String.format("%06d\n", number)
        var res = String.format("%06d", py[i].first) + String.format("%06d\n", number)
        pw.print(res)
    }
    return result
}