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 {
  object Scanner {
    private val buf = new Array[Byte](1024); private var ptr = 0; private var len = 0
    @inline private def isPrintableChar(c: Int): Boolean = 33 <= c && c <= 126
    @inline private def hasNextByte(): Boolean =
      if (ptr >= len) { ptr = 0; len = System.in.read(buf); len > 0 } else { true }
    @inline private def hasNext(): Boolean = {
      while (hasNextByte() && !isPrintableChar(buf(ptr))) ptr += 1
      hasNextByte()
    }
    @inline private def readByte(): Byte =
      if (hasNextByte()) { val res = buf(ptr); ptr += 1; res } else { -1 }
    def next(): String = {

      if(!hasNext()) ???
      val sb = new StringBuilder; var b = readByte()
      while (isPrintableChar(b)) { sb.append(b.toChar); b = readByte() }
      sb.toString
    }
    def nextInt(): Int = {
      val n = nextLong()
      if (n < Int.MinValue || Int.MaxValue < n) ???
      n.toInt
    }
    def nextLong(): Long = {
      if(!hasNext()) ???
      var minus = false; var b = readByte()
      if (b == '-') { minus = true; b = readByte() }
      def go (b: Byte, n: Long = 0): Long =
        if ('0' <= b && b <= '9') { go(readByte(), n * 10 + b - '0') }
        else if (minus) { -n } else { n }
      go(b)
    }
    def nextDouble(): Double = next.toDouble
  }

  val (n, m) = (Scanner.nextInt(), Scanner.nextInt())

  val lines = Array.fill(m,2)(Scanner.nextInt()).zipWithIndex.map {
    case (Array(p, y), i) => Array(i, p, y)
  }
  def order(a1: Array[Int], a2: Array[Int]): Boolean =
    if (a1(1) == a2(1)) a1(2) < a2(2) else a1(1) < a2(1)

  def convert(p: Int, order: Int) = f"${p}%06d${order}%06d"

  var currentP = 0
  var currentIndex = 1

  def next(a: Array[Int]) = {
    if (a(1) == currentP) currentIndex = currentIndex + 1 else {
      currentIndex = 1
      currentP = a(1)
    }
    Array(a(0), a(1), currentIndex)
  }

  lines
    .sortWith(order)
    .map(next)
    .sortBy(_(0))
    .foreach(a => println(convert(a(1), a(2))))



  //  val (n, m) = (Scanner.nextInt(), Scanner.nextInt())
//
//  val lines = Array.fill(m,2)(Scanner.nextInt()).map {
//    case Array(p, y) => (p, y)
//  }
////
////  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
}