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.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;

public class Program
{
    public void Proc()
    {
        int[] inpt = ScanInt();

        int kenCount = inpt[0];
        int cityCount = inpt[1];

        StringBuilder ans = new StringBuilder();


        SortedDictionary<int, SortedDictionary<long, int>> dic = new SortedDictionary<int, SortedDictionary<long, int>>();
        for (int i = 0; i < cityCount; i++) {
            long[] tmp = ScanLong();
            int ken = (int)tmp[0];
            long year = tmp[1];
            if(!dic.ContainsKey(ken)) {
                dic.Add(ken, new SortedDictionary<long, int>());
            }
            dic[ken].Add(year, i);
        }

        string[] list = new string[cityCount];
        foreach(int ken in dic.Keys) {
            int serial = 1;
            string kenID = ken.ToString().PadLeft(6, '0');
            foreach(int year in dic[ken].Keys) {
                int key = dic[ken][year];
                string id = kenID + serial.ToString().PadLeft(6, '0');
                list[key] = id;
                serial++;
            }
        }
        foreach(string id in list) {
            ans.AppendLine(id);
        }
        Console.Write(ans.ToString());
    }


    private int[] ScanInt() {
        return Reader.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();
    }

    private long[] ScanLong() {
        return Reader.ReadLine().Split(' ').Select(a => long.Parse(a)).ToArray();
    }

    private string[] ScanStr() {
        return Reader.ReadLine().Split(' ').ToArray();
    }

    public class Reader
    {
        static StringReader sr;
        public static bool IsDebug = false;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (sr == null)
                {
                    sr = new StringReader(InputText.Trim());
                }
                return sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        private static string InputText = @"


2 3
2 55
2 77
2 99


";
    }

    public static void Main(string[] args)
    {
#if DEBUG
        Reader.IsDebug = true;
#endif
        Program prg = new Program();
        prg.Proc();
    }
}