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;

public class HelloWorld
{
    class data
    {
        public int i;
        public int p;
        public int y;
        public int id;
    }

    static public void Main ()
    {
        var input = Console.ReadLine().Split(' ');
        var n = int.Parse(input[0]);
        var m = int.Parse(input[1]);

        var data = new List<data>();
        for (int i = 0; i < m; i++)
        {
            // (pi, yi)
            var line = Console.ReadLine().Split(' ');
            int p = int.Parse(line[0]);
            int y = int.Parse(line[1]);
            var t = new data
            {
                i = i,
                p = p,
                y = y,
                id = 0,
            };
            data.Add(t);
        }
        var pcount = new Dictionary<int, int>();

        data = data.OrderBy(d => d.y).ToList();
        
        for (int i = 0; i < m; i++)
        {
            var t = data[i];
            if (pcount.ContainsKey(t.p))
            {
                pcount[t.p]++;
            }
            else
            {
                pcount[t.p] = 1;
            }
            t.id = pcount[t.p];
        }

        data = data.OrderBy(d => d.i).ToList();
        
        for (int i = 0; i < m; i++)
        {
            var s = string.Format("{0:000000}{1:000000}", data[i].p, data[i].id);
            Console.WriteLine(s);
        }
    }
}