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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Linq;
using System.Collections.Generic;
class Program
{
  static void Main(string[] args)
  {
    var rule = Console.ReadLine().Split(' ').Select(x=>int.Parse(x)).ToArray();

    //市/県番号/年
    List<int[]> table = new List<int[]>();

    for(int i=0;i<rule[1];i++){
      var work = Console.ReadLine().Split(' ').Select(x=>int.Parse(x)).ToArray();
      table.Add(new int[]{i, work[0],work[1]});
    }
    
    string[] result = new string[rule[1]];
    for(int prefecture=1; prefecture<=rule[1];prefecture++){
      var rows = table.Where(x=>x[1]==prefecture).OrderBy(x=>x[2]);
      int rowNo=1;
      foreach(var row in rows){
        result[row[0]] = String.Format("{0:000000}", row[1]) + String.Format("{0:000000}", rowNo);
        rowNo++;
      }
    }

    foreach(var no in result){
      Console.WriteLine(no);
    }
  }
}