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: Wrong Answer)

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

namespace book
{
    //6章
    //再帰・分割統治法
    //ALDS1_4_D(Allocation)
    /*class Program
    {
        static void Main()
        {
            long[] input = Console.ReadLine().Split().Select(long.Parse).ToArray();
            long n = input[0];
            long k = input[1];
            List<long> weight = new List<long>();
            for (long i =0; i<n;i++)
            {
                weight.Add(long.Parse(Console.ReadLine()));
            }
        }
        static void solve()
        {
            long left = 0;
            long right = 10000000000;
            long mid = 0;
            while (right - left > 1)
            {
                mid = (right + left) / 2;
                
            }
        }
        static int check(long P,int n)
        {
            int i = 0;
            for (int j =0;j<;j++)
            {

            }
        }
    }*/
    //113C-ID
    class Program
    {
        static void Main()
        {
            long[] cin = Console.ReadLine().Split().Select(long.Parse).ToArray();
            long N = cin[0];
            long M = cin[1];
            List<Data> list = new List<Data>();
            for (int i = 0; i< M;i++)
            {
                Data data = new Data();
                var temp = Console.ReadLine().Split().Select(long.Parse).ToArray();
                data.ID = i;
                data.pref = temp[0];
                data.year = temp[1];
                list.Add(data);
            }
            var sortedlist = list.OrderBy(n => n.pref).OrderBy(m => m.year).ToList();
            var ans = rep(sortedlist);
            ans = ans.OrderBy(n => n.ID).ToList();
            foreach (Data m in ans)
            {
                Console.Write("{0:D6}",m.pref);
                Console.WriteLine("{0:D6}", m.year);
            }
        }
        static List<Data> rep(List<Data> sortlist)
        {
            long rank = sortlist.First().pref;
            var a = 1;
            foreach (Data list in sortlist)
            {
                if (list.pref == rank)
                {
                    list.year = a;
                    a++;
                }
                else
                {
                    a = 1;
                    rank++;
                    list.year = a;
                }
            }
            return sortlist;
        }
    }
    class Data
    {
        public long ID { get; set; }
        public long pref { get; set; }
        public long year { get; set; }
    }
}