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;

namespace Practice
{
    class Program
    {
        static void Main(string[] args)
        {
            SolveA();
            //SolveB();
            //SolveC();
            //SolveD();
        }
        private const long MOD = 1000000007;
        private struct Data
        {
            public int idx;
            public int year;
        }
        static void SolveA()
        {
            var nm = ReadAndParseIntArr();
            int n = nm[0];
            int m = nm[1];
            int[] p = new int[m];
            int[] y = new int[m];
            for(int i=0;i<m;++i)
            {
                var tmp = ReadAndParseIntArr();
                p[i] = tmp[0];
                y[i] = tmp[1];
            }

            var hash = new Dictionary<int, List<Data>>();// key 県id、value yearの配列

            long[] ids = new long[m];
            for(int i=0;i<m;++i)
            {
                if(!hash.ContainsKey(p[i]))
                {
                    hash[p[i]] = new List<Data>();
                }

                var list = hash[p[i]];
                list.Add(new Data() { idx = i, year = y[i] });
            }

            foreach(var pair in hash)
            {
                pair.Value.Sort((a,b)=>a.year.CompareTo(b.year));
            }

            foreach(var pair in hash)
            {
                int ken = pair.Key;
                var datas = pair.Value;
                for(int i=0;i<datas.Count;++i)
                {
                    Data data = datas[i];
                    long id = ken * 1000000 + i + 1;

                    ids[data.idx] = id;
                }
            }
            foreach(long id in ids)
            {
                Console.WriteLine(id.ToString("D12"));
            }
        }
        
        
        #region よく使う便利関数
        private static bool isPrime(long x)
        {
            if( x == 2) { return true; }
            if( x < 2 || x % 2 == 0) { return false; }
            long i = 3;
            while( i * i <= x)
            {
                if( x % i == 0) { return false; }
                i = i + 2;
            }
            return true;
        }
        private static long lcm(long x, long y)
        {
            return x / gcd(x, y) * y;
        }
        private static long gcd(long x, long y)
        {
            return y > 0 ? gcd(y, x % y) : x;
        }

        private static int ReadAndParseInt()
        {
            return int.Parse(Console.ReadLine());
        }
        private static int[] ReadAndParseIntArr()
        {
            return Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
        }
        private static long ReadAndParseLong()
        {
            return long.Parse(Console.ReadLine());
        }
        private static long[] ReadAndParseLongArr()
        {
            return Array.ConvertAll(Console.ReadLine().Split(' '), long.Parse);
        }
        #endregion
    }
}