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.Linq;
using System.Collections.Generic;
public class P {
    public static void Main() {
        var s = Console.ReadLine().Split(' ');
        int N = int.Parse(s[0]), M = int.Parse(s[1]);
        //int p, y;
        List<int>[] vs = new List<int>[N];
        for(int i=0;i<N;i++)vs[i]=new List<int>();
        List<long> al = new List<long>();
        for (int i = 0;i<M;i++){
            s=Console.ReadLine().Split(' ');
            vs[int.Parse(s[0])-1].Add(int.Parse(s[1]));
            al.Add(100000*(int.Parse(s[0])-1)+int.Parse(s[1]));//あとで探索とかする
        }
        foreach (List<int> ts in vs) {
            ts.Sort();
        }
        for (int i = 0;i<M;i++){
        	long Ind = al[i]/100000;
            for (int f = 0;f<vs[Ind].Sum(x => 1);f++){
                int[] a = vs[Ind].ToArray();
                if (a[f]==al[i]-100000*Ind) Console.WriteLine((Ind+1).ToString().PadLeft(6,'0')+(f+1).ToString().PadLeft(6,'0'));
            }
        }

    }
}