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;

namespace ABC113
{

    class City
    {
        public int Index { get; set; }
        public int Prefecture { get; set; }
        public int Year { get; set; }
        public string Number { get; set; }

        public City(int i, int p, int y)
        {
            this.Index = i;
            this.Prefecture = p;
            this.Year = y;
        }
    }

    class C
    {
        static void Main(string[] args)
        {
            int[] input = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int N = input[0];
            int M = input[1];

            string[] py;
            //City[] cArray = new City[M];
            List<Tuple<int, int, int>> tupleList = new List<Tuple<int, int, int>>();
            for (int i = 0; i < M; i++)
            {
                py = Console.ReadLine().Split();
                //City c = new City(i, int.Parse(py[0]), int.Parse(py[1]));
                //cArray[i] = c;
                tupleList.Add(Tuple.Create(i, int.Parse(py[0]), int.Parse(py[1])));
            }
            //var newArray = cArray.GroupBy(x => x.Prefecture);
            //newArray.OrderBy(x => x)
            var newList = tupleList.OrderBy(x => x.Item2).ThenBy(x => x.Item3);

            string[] Res = new string[M];
            int prefecture = newList.First().Item2;
            int index = 1;


            foreach (var i in newList)
            {
                if (i.Item2 != prefecture) index = 1;
                Res[i.Item1] = i.Item2.ToString().PadLeft(6, '0') + index.ToString().PadLeft(6, '0');
                index++;
            }

            foreach (var i in Res)
            {
                Console.WriteLine(i);
            }

        }

    }
}