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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ABC113C
{
    static class MainClass
    {

        public static void Main(string[] args)
        {


            string[] input1 = Console.ReadLine().Split(' ');

            int N = int.Parse(input1[0]);
            int M = int.Parse(input1[1]);


            int[][] PY = new int[M][];
            for (int i = 0; i < M; i++)
            {
                string[] input2 = Console.ReadLine().Split(' ');
                int[] pandy = new int[4];

                pandy[0] = int.Parse(input2[0]);//県
                pandy[1] = int.Parse(input2[1]);//年
                pandy[2] = i; //もとのindex
                pandy[3] = 0; //市の中の順番
                PY[i] = pandy;
            }

            //PY.ToList().Sort((a, b) => a[0] - b[0]);//県でソート

       
            List<int[]> dst = PY.ToList().OrderBy(a => a[0]).ThenBy(a => a[1]).ToList() ;
        

            List<int> grp = dst.GroupBy(a => a[0]).Select(c => c.Count()).ToList();

            int diff = 0;

            for (int i = 0; i < M;i++){
                if(i!=0){
                    if(dst[i][0] != dst[i-1][0]){
                        diff = diff + grp[0];
                        grp.RemoveAt(0);
                    }
                }

                dst[i][3] = int.Parse(string.Format("{0,10}",i - diff + 1));
            }

            List<string> ans = dst.ToList().OrderBy(a => a[2]).ToList().Select(a => string.Format("{0:D6}", a[0]) + String.Format("{0:D6}",a[3])).ToList();

            foreach(var items in ans){
                Console.WriteLine(items);
            }            
            return;

        }


    }

}