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;
using System.Diagnostics;
using System.IO;
using System.Linq;

namespace ID
{
    class Program
    {
        public static void Main(string[] args)
        {
            using (var sc = new SetConsole())
            {
                var nm = GetArrayInput();
                var dic = new Dictionary<string, SortedSet<int>>();
                var list = new List<Tuple<string, int>>();
                for (int i = 0; i < nm[1]; i++)
                {
                    var py = Console.ReadLine().Split();
                    int y = py[1].ToInt();
                    list.Add(Tuple.Create(py[0], y));
                    if (!dic.ContainsKey(py[0]))
                    {
                        dic.Add(py[0], new SortedSet<int>(new int[] { y }));
                    }
                    else
                    {
                        dic[py[0]].Add(y);
                    }
                }

                list.ForEach(tuple =>
                {
                    var count = 1;
                    foreach (var item in dic[tuple.Item1])
                    {
                        if (tuple.Item2 == item) { break; }
                        ++count;
                    }
                    CWrite($"{tuple.Item1.PadLeft(6, '0')}{count.ToString().PadLeft(6, '0')}");
                });
            }
        }
        static int[] GetArrayInput() => Console.ReadLine().StringToIntArray();
        static int GetNumberInput() => Console.ReadLine().ToInt();
        static void CWrite(string str) => Console.WriteLine(str);
    }

    class SetConsole : IDisposable
    {
        public SetConsole()
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
        }
        public void Dispose()
        {
            Console.Out.Flush();
        }
    }

    static class ExtentionsLibrary
    {
        public static int[] StringToIntArray(this string str) =>
            str.Split().Select(int.Parse).ToArray();
        public static int ToInt(this string str) => int.Parse(str);
    }
}