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: Time Limit Exceeded)

using System;
using System.Collections.Generic;
class Program
{
	static void Main(string[] args)
	{
// 		// 整数の入力
// 		int a = int.Parse(Console.ReadLine());
// 		// スペース区切りの整数の入力
// 		string[] input = Console.ReadLine().Split(' ');
// 		int b = int.Parse(input[0]);
// 		int c = int.Parse(input[1]);
// 		// 文字列の入力
// 		string s = Console.ReadLine();
// 		//出力
// 		Console.WriteLine((a+b+c) + " " + s);
        string[] input = Console.ReadLine().Split(' ');
        int n = int.Parse(input[0]);
        int m = int.Parse(input[1]);
        var map = new Dictionary<int,  List<int>>();
        
        int[] pinput = new int[m];
        int[] yinput = new int[m];
        
        for(int i = 0;i < m;i++){
            string[] ini = Console.ReadLine().Split(' ');
            int p =  int.Parse(ini[0]);
            int y =  int.Parse(ini[1]);
            if(!map.ContainsKey(p)){
                var list =  new List<int>();
                map.Add(p, list);
            }
            map[p].Add(y);
            pinput[i] = p;
            yinput[i] = y;
        }

        foreach (var key in map.Keys) {
            map[key].Sort();
        }

        for(int i = 0;i < m;i++){
            string p = String.Format("{0:000000}", pinput[i]);
            string y = String.Format("{0:000000}", map[pinput[i]].IndexOf(yinput[i])+1);
            Console.WriteLine(p + y);
        }
	}
}