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;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static void Main(string[] args)
    {
    	var sc = new Scanner();
    	int n = sc.NextInt();
    	int m = sc.NextInt();
    	var dic = new Dictionary<int, List<int>>();
    	var pairs = new List<Tuple<int, int>>();
    	for (int i = 0; i < m; i++)
    	{
    		int p = sc.NextInt();
    		if (!dic.ContainsKey(p)) dic.Add(p, new List<int>());
    		int y = sc.NextInt();
    		dic[p].Add(y);
    		pairs.Add(Tuple.Create(p, y));
    	}
    	var res = new Dictionary<Tuple<int, int>, string>();
    	foreach (var item in dic.OrderBy(p => p.Key))
    	{
    		item.Value.Sort();
    		for (int i = 0; i < item.Value.Count;i++)
    		    res.Add(Tuple.Create(item.Key, item.Value[i]), string.Format("{0:D6}{1:D6}", item.Key, i + 1));
    	}
    	
    	foreach (var item in pairs)
    	    Console.WriteLine(res[item]);
    }
}

class Scanner
{
    int index = -1;
    string[] buf;

    public Scanner()
    {
    }

    public int NextInt()
    {
        CheckNext();
        return int.Parse(buf[index++]);
    }
        
    public long NextLong()
    {
    	CheckNext();
    	return long.Parse(buf[index++]);
    }

    public string NextString()
    {
        CheckNext();
        return buf[index++];
    }

    private void CheckNext()
    {
        if (index >= 0 && index < buf.Length) return;

        buf = Console.ReadLine().Split(' ');
        index = 0;
    }
}