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.Linq;
using System.Text;
using System.Threading.Tasks;

namespace abc113
{
    class abc113c
    {
        static void Main(string[] args)
        {
            var NM = Console.ReadLine().Split();
            var N = int.Parse(NM[0]);
            var M = int.Parse(NM[1]);

            ThirdIdea(N, M);
        }

        static void ThirdIdea(int N, int M)
        {
            var P = new List<int>(M+1);
            P.Add(0);
            var Y = new List<int>(M+1);
            const int YMax = 1000000001;
            Y.Add(YMax);
            for (var i = 1; i <= M; ++i)
            {
                var PY = Console.ReadLine().Split();
                P.Add(int.Parse(PY[0]));
                Y.Add(int.Parse(PY[1]));
            }

            var histories = Enumerable.Range(0, N + 1).Select(x => new List<int>()).ToList();
            for (var i=1; i<=M; ++i)
            {
                histories[P[i]].Add(Y[i]);
            }
            for (var i = 1; i <= N; ++i)
            {
                histories[i] = histories[i].OrderBy(x => x).ToList();
            }
            for (var i=1;i<=M;++i)
            {
                var num = histories[P[i]].FindIndex(x => x == Y[i]) + 1;
                Console.WriteLine($"{P[i]:D6}{num:D6}");
            }
        }

        static void SecondIdea(int N, int M)
        {
            var tuples = new List<Tuple<int, int>>(M);
            for (var i = 0; i < M; ++i)
            {
                var PY = Console.ReadLine().Split();
                tuples.Add(Tuple.Create(int.Parse(PY[0]), int.Parse(PY[1])));
            }

            var histories = Enumerable.Range(0, N + 1).Select(x => new List<int>()).ToList();
            foreach (var t in tuples)
            {
                histories[t.Item1].Add(t.Item2);
            }
            for (var i = 1; i <= N; ++i)
            {
                histories[i] = histories[i].OrderBy(x => x).ToList();
            }
            foreach (var t in tuples)
            {
                var num = histories[t.Item1].FindIndex(x => x == t.Item2) + 1;
                Console.WriteLine($"{t.Item1:D6}{num:D6}");
            }
        }

        static void FirstIdea(int N, int M)
        {
            var tuples = new List<Tuple<int, int>>(M + 1);
            tuples.Add(Tuple.Create(0, 0));
            for (var i = 1; i <= M; ++i)
            {
                var PY = Console.ReadLine().Split();
                tuples.Add(Tuple.Create(int.Parse(PY[0]), int.Parse(PY[1])));
            }
            for (var i = 1; i <= M; ++i)
            {
                var num = tuples.Where(t => t.Item1 == tuples[i].Item1)
                            .Select(u => u.Item2)
                            .OrderBy(y => y)
                            .ToList()
                            .FindIndex(x => x == tuples[i].Item2) + 1;

                Console.WriteLine($"{tuples[i].Item1:D6}{num:D6}");
            }
        }
    }
}