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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CS.Solve
{
    class Program
    {
        static void Main(string[] args)
        {
            var NM = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            List<int[]> x = new List<int[]>();
            foreach (var i in Enumerable.Range(0, NM[1]))
            {
                var tmp = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
                x.Add(new int[] { tmp[0], tmp[1], i, 0 });
            }
            var y = x.OrderBy(p => p[0]).OrderBy(p => p[1]).ToArray();

            y[0][3] = 0;
            var pi = y[0][0];
            var junban = 0;

            foreach (var tmp in y)
            {
                if(tmp[0] == pi)
                {
                    tmp[3] = junban;
                    junban++;
                }
                else
                {
                    junban = 0;
                    tmp[3] = 0;
                }
            }
            foreach(var tmp in y.OrderBy(p => p[2]))
            {
                Console.WriteLine("{0:000000}{1:000000}", tmp[0], tmp[3]+1);
            }

        }
    }
}