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: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace _0030
{

    struct ID
    {
        internal int ken;
        internal int rank;
    }
    
    class Program
    {
        
        
        static void Main(string[] args)
        {

            string[] str = Console.ReadLine().Split(' ');
            int n = int.Parse(str[0]);
            int m = int.Parse(str[1]);

            var ans = new ID[m + 1];

            var data = new Dictionary<long, int>[n + 1];
            var sortdata = new Dictionary<long, int>[n + 1];

            //インスタンスを作成
            for(int i = 1; i <= n; i++)
            {
                data[i] = new Dictionary<long, int>();
                sortdata[i] = new Dictionary<long, int>();
            }

            int p;
            long y;
            //i市情報からデータを設定
            for(int i = 1; i <= m; i++)
            {
                str = Console.ReadLine().Split(' ');
                p = int.Parse(str[0]);
                y = long.Parse(str[1]);

                data[p][y] = i;

            }

            //各県に対してkey(年数)を基準にソート
            for(int i = 1; i <= n; i++)
            {
                sortdata[i] = data[i].OrderBy((x) => x.Key).ToDictionary(x => x.Key, x => x.Value);                
            }

            
            int cnt = 0;
            for(int i = 1; i <= n; i++)
            {
                cnt = 1;
                foreach(var s in sortdata[i])
                {
                    //Console.WriteLine($"i = {i} {s.Key} {s.Value}");
                    ans[s.Value].ken = i;
                    ans[s.Value].rank = cnt;
                    cnt++;
                }
            }

            for(int i = 1; i <= m; i++)
            {
                Console.WriteLine(string.Format("{0:d6}{1:d6}", ans[i].ken, ans[i].rank));
            }

        }
    }
}