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;
namespace _113C
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] str1 = Console.ReadLine().Split(' ');
            int N = int.Parse(str1[0]);//prefecture
            int M = int.Parse(str1[1]);//city
            int[][] str2 = new int[M][];
            for (int i = 0; i < M; i++)
            {
                str2[i] = new int[4];
                str2[i][0] = i;
                string[] str3 = Console.ReadLine().Split(' ');
                str2[i][1] = int.Parse(str3[0]);//prefecture
                str2[i][2] = int.Parse(str3[1]);

            }
            Array.Sort(str2, (x, y) => x[2] - y[2]);
            int[][] prefects = new int[N][];
            int[] cities = new int[N];
            for (int k = 0; k < N; k++)
            {
                cities[k] = 0;
            }

            for (int j = 0; j < M; j++)
            {

                cities[str2[j][1]-1]= cities[str2[j][1]-1]+1;
                str2[j][3] = cities[str2[j][1]-1];
            }

            for (int j = 0; j < M; j++)
            {


                string strb = "000000" + str2[j][1].ToString();
                strb = strb.Substring(strb.Length - 6, 6);
                string stra = "000000" + str2[j][3].ToString();
                stra = stra.Substring(stra.Length - 6, 6);
                Console.WriteLine(strb + stra);
            }

        }
    }
}