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.Linq;
        using System.Collections.Generic;
        using static System.Math;

　class city
    {
        public int CityPref;
        public int CityID;

        public city(int cityPref, int cityId)
        {
            this.CityPref = cityPref;
            this.CityID = cityId;
        }
    }
        public class Program
        {
            public static void Main(string[] args)
            {
            int[] nm = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            List<city> cityList = new List<city> { };

            for (int i = 0; i < nm[1]; i++)
            {
                int[] stock = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
                cityList.Add(new city(stock[0], stock[1]));
            }

            IOrderedEnumerable<city> sortCity = cityList.OrderBy(x => x.CityPref).ThenBy(y => y.CityID);

            int citynum = 1;
            foreach (city c in sortCity)
            {
                int prefCode = c.CityPref;
                string strPref = prefCode.ToString();
                string strCity = citynum.ToString();
                if(prefCode != citynum)
                {
                    citynum = 1;
                }

                while (strPref.Length < 6)
                {
                    strPref  = "0" + strPref;
                }

                while (strCity.Length < 6)
                {
                    strCity = "0" + strCity;
                }
                Console.WriteLine(strPref + strCity);

                int stock = prefCode;
                citynum++;
            }
            }
        }