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;
using System.Collections.Generic;
using System.Text;

class Program
{
    static void Main(string[] args)
    {

        // 入力
        long[] nm = Console.ReadLine().Split().Select(long.Parse).ToArray();
        var n = nm[0];
        var m = nm[1];

        long[] p = new long[m];
        long[] y = new long[m];
        for (int i = 0; i < m; i++)
        {
            long[] tmp = Console.ReadLine().Split().Select(long.Parse).ToArray();
            p[i] = tmp[0];
            y[i] = tmp[1];
        }

        long[] sp = new long[p.Length];
        long[] sy = new long[y.Length];
        Array.Copy(p, sp, p.Length);
        Array.Copy(y, sy, y.Length);

        Array.Sort(sy, sp);
        Array.Sort(sp, sy);
        long count = 1;
        string ans = "";
        var dic = new Dictionary<Tuple<long, long>, string>(){};
        for (int i = 0; i < m; i++)
        {
            if (i > 0 && sp[i - 1] != sp[i])
            {
                count = 1;
            }

            ans = sp[i].ToString("d6") + count.ToString("d6");
            dic.Add(new Tuple<long, long>(sp[i], sy[i]), ans);
            count++;
        }

        for (int i = 0; i < m; i++)
        {
            Console.WriteLine(dic[new Tuple<long, long>(p[i], y[i])]);
        }


    }
}