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: Time Limit Exceeded)

object Main extends App {

  val (n, m) = readLine.split(" ").map(_.toInt) match {
    case Array(n, m) => (n, m)
  }

  val lines: Seq[(Int, Int)] = (1 to m)
    .map(_ =>
      readLine.split(" ").map(_.toInt) match {
        case Array(p, y) => (p, y)
      })

  val map: Map[Int, Map[Int, Int]] =
    lines
      .groupBy(_._1)
      .mapValues(
        _.sortBy(_._2).zipWithIndex.map {
          case ((p, y), index) => (y, index + 1)
        }.toMap
      )

  def convert(p: Int, order: Int) = f"${p}%06d${order}%06d"
  val pw = new java.io.PrintWriter(System.out)
  lines.map { case (p, y) => convert(p, map(p)(y)) }.foreach{ res =>
    pw.println(res)
  }
  pw.flush
}