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._
import java.io.PrintWriter
import java.util.Arrays
object Main extends App {
  val sr = new StdinReader
  val n, m = sr.nextInt
  case class City(id: Int, p: Int, year: Int, var no: Int = 0)
  val pys = (1 to m).map{i => City(i, sr.nextInt, sr.nextInt)}
  def numbering(cities: Seq[City]): Unit =
    cities.sortBy(_.year).zipWithIndex.foreach {case (c, no) => c.no = no + 1}
  val pyMap = pys.groupBy(_.p).values.foreach(numbering)
  val w = new PrintWriter(System.out)
  val f = new java.text.DecimalFormat("000000000000")
  pys.foreach {c => w.println(f.format(c.p * 1000000L + c.no)) }
  w.flush
}

class StdinReader {
  val is = System.in
  val buffer = new Array[Byte](1024 * 1024)
  var size = 0
  var pos = 0

  private def readByte: Byte = {
    if (pos >= size) {
      pos = 0;
      size = is.read(buffer);
    }
    if (size < 0) -1
    else {
      val ret = buffer(pos)
      pos += 1
      ret
    }
  }

  def nextInt: Int = {
    @scala.annotation.tailrec
    def r(i: Int, reading: Boolean): Int = {
      readByte match {
        case '-' => r(i * -1, true)
        case b if '0' <= b && b <= '9' => r(i * 10 + (b - '0'), true)
        case _ => if (reading) i else r(i, false)
      }
    }
    r(0, false)
  }
}