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: Runtime Error)

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);
			var Y = new List<int>(M);
			const int YMax = 1000000001;
			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 = new int[100001,YMax];
			for (var i=0; i!=M; ++i)
			{
				histories[P[i],Y[i]]=1;
			}
			for (var i = 1; i <= N; ++i)
			{
				var num=1;
				for(var j=1;j<=YMax-1;++j){
					if(histories[j,i]==1){
						histories[j,i]=num++;
					}
				}
			}
			for (var i=1;i<=M;++i)
			{
				var num = histories[Y[i],P[i]];
				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}");
		//    }
		//}
	}
}