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 Scala (2.11.7) (judge verdict: Accepted)

import scala.io.{StdIn => in}

object Main extends App {
  val out = new java.io.PrintWriter(System.out)
  val Array(n, m) = in.readLine.split(" ").map(_.toInt)

  case class Id(i: Int, p: Int, x: Int)

  val city = Iterator.continually(in.readLine)
    .take(m)
    .map(_.split(" "))
    .zipWithIndex
    .map(a => new Id(a._2.toInt, a._1(0).toInt, a._1(1).toInt))
    .toArray

  val sortedCity = city
    .sorted {
      new Ordering[Id] {
        def compare(x: Id, y: Id): Int = (
          x.p.compareTo(y.p) match {
            case 0 => x.x.compareTo(y.x)
            case c => c
          })
      }
    }
    .scanLeft((0, 0, 0)) { (acc, city) =>
        if(acc._2 == city.p) (city.i, acc._2, acc._3 + 1)
        else (city.i, city.p, 1)
      }
    .tail
    .sortBy(_._1)

  sortedCity.foreach { id =>
        val p = Array.fill(6 - rec(0, id._2))('0').mkString
        val x = Array.fill(6 - rec(0, id._3))('0').mkString
        out.println(p + id._2 + x + id._3)
      }
  out.flush

  def rec(cnt:Int, v: Int):Int = {
    if(v == 0) cnt
    else rec(cnt+1, v / 10)
  }
}