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)

// デバッグ実行：Ctrl+F5

using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        String line;
        line = Console.ReadLine();
        String[] words = line.Split(' ');
        int N = int.Parse(words[0]);
        int M = int.Parse(words[1]);
        List<Tuple<int, int>> datas = new List<Tuple<int, int>>();
        List<Tuple<int, int>> before = new List<Tuple<int, int>>();
        Dictionary<Tuple<int, int>, string> dict = new Dictionary<Tuple<int, int>, string>();

        for (int i = 0; i < M; i++)
        {
            line = Console.ReadLine();
            words = line.Split(' ');
            Tuple<int, int> data = new Tuple<int, int>(int.Parse(words[0]), int.Parse(words[1]));
            datas.Add(data);
            before.Add(data);
            dict.Add(data, "0");
        }

        datas.Sort((a, b) => b.Item1 == a.Item1 ? a.Item2 - b.Item2 : (a.Item1 > b.Item1 ? 1 : -1));
        int now_P = 0;
        int count = 0;
        for (int i = 0; i < M; i++)
        {
            if (now_P != datas[i].Item1)
            {
                // 入れ替え
                now_P = datas[i].Item1;
                count = 0;
            }
            count++;
            dict[datas[i]] = String.Format("{0:D6}{1:D6}", datas[i].Item1, count);

        }
        for(int i = 0; i < M; i++)
        {
            Console.WriteLine(dict[before[i]]);
        }
    }

}