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;
using System.Collections.Generic;

class Program
{
    public static void Main()
    {
        string[] str = Console.ReadLine().Split(' ');
        int N = int.Parse(str[0]);
        int M = int.Parse(str[1]);
        List<Tuple<int, int>> Table = new List<Tuple<int, int>>() { Capacity = M };
        for(int i = 0; i < M; i++)
        {
            str = Console.ReadLine().Split(' ');
            Tuple<int, int> t = new Tuple<int, int>(int.Parse(str[0]), int.Parse(str[1]));
            Table.Add(t);
        }
        Table.Sort((x,y)=>
        {
            if (x.Item1 - y.Item1 != 0)
                return x.Item1 - y.Item1;
            else
                return x.Item2 - y.Item2;
        });
        int pref = Table[0].Item1;
        int tid = 1;
        for(int i = 0; i < M; i++)
        {
            if(pref == Table[i].Item1)
            {
                Console.WriteLine(pref.ToString().PadLeft(6, '0') + tid.ToString().PadLeft(6,'0'));
                tid++;
            }
            else
            {
                pref = Table[i].Item1;
                tid = 1;
                Console.WriteLine(pref.ToString().PadLeft(6, '0') + tid.ToString().PadLeft(6, '0'));
                tid++;
            }
        }
    }
}