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.Generic;

class MondaiC
{
    static void Main()
    {
        var line = Console.ReadLine().Split(' ').Select(x => Int32.Parse(x)).ToArray();
        var N = line[0];
        var M = line[1];
        var index = new int[M];
        var city = new long[M];
        var pri=new int[M];
        for (int i=0;i<M;++i)
        {
            var l = Console.ReadLine().Split(' ').Select(x=>Int32.Parse(x)).ToArray();
            pri[i] = l[0];
            city[i] = l[1];
            index[i] = i;
        }
        Array.Sort(city,index);
        var ans = new string[M];
        var priCount = new int[line[0] + 1];
        for (int i = 0; i < M; ++i)
        {
            priCount[pri[i]]++;
            ans[index[i]]= string.Format("{0:D6}", pri[i])+ string.Format("{0:D6}", priCount[pri[i]]);
        }
        foreach (var a in ans) {
            Console.WriteLine(a);
        }
    }
}