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.Text;
using System.Numerics;
using System.IO;

namespace SolutionCS
{
    class Program
    {
        public class City : IComparable<City>
        {
            public static bool compare_index = false;

            public City(int p, int y, int ind)
            {
                index = ind;
                prefecture = p;
                year = y;
            }

            public int index { get; private set; }
            public int prefecture { get; private set; }
            public int year { get; private set; }
            public int order { get; set; }

            public int CompareTo(City e)
            {
                if (compare_index)
                {
                    return index.CompareTo(e.index);
                }

                int y = prefecture.CompareTo(e.prefecture);
                if (y == 0)
                {
                    y = year.CompareTo(e.year);
                }

                return y;
            }
        }

        static void Main(string[] args)
        {
            string[] s = Console.ReadLine().Split(' ');
            int N = int.Parse(s[1]);

            List<City> listC = new List<City>();

            for (int i = 0; i < N; i++)
            {
                s = Console.ReadLine().Split(' ');

                City c = new City(int.Parse(s[0]), int.Parse(s[1]), i);
                listC.Add(c);
            }

            int ord = 1;
            int prev = -1;
            listC.Sort();
            for (int i = 0; i < N; i++)
            {
                City c = listC[i];
                if ( c.prefecture != prev)
                {
                    ord = 0;
                    prev = c.prefecture;
                }

                ord++;

                c.order = ord;
            }

            City.compare_index = true;
            listC.Sort();


            for (int i = 0; i < N; i++)
            {
                City c = listC[i];
                Console.WriteLine("{0:D6}{1:D6}", c.prefecture, c.order);
            }
        }
    }
}