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;
using static System.Console;
using System.Text;
using System.IO;
using static System.Math;
namespace AtCoder
{
    class Program
    {
        static public long[] Sarray() { return ReadLine().Split().Select(long.Parse).ToArray(); }
        static public List<long> Slist() { return ReadLine().Split().Select(long.Parse).ToList(); }

        //static long Mod = (long)1e9 + 7;
        static void Main(string[] args)
        {
            //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
            var NM = Sarray();
            var N = NM[0];
            var M = NM[1];
            var cinfo = new List<Tuple<long, long, long, string>>();//index,県(P),誕生年(Y),認識番号
            for (var i = 0L; i < M; ++i)
            {
                var py = Sarray();
                var p = py[0];
                var y = py[1];
                cinfo.Add(Tuple.Create(i, p, y, string.Empty));
            }
            cinfo.Sort((l, r) => (int)(l.Item3 - r.Item3));
            var cg = cinfo.GroupBy(c => c.Item2).ToList();
            var scinfo = new List<Tuple<long, long, long, string>>();
            for(var i=0;i<cg.Count();++i)
            {
                var num = 1;
                foreach (var c in cg[i])
                {
                    scinfo.Add(Tuple.Create(c.Item1,c.Item2,c.Item3,$"{c.Item2:d6}{num:d6}"));
                    num++;
                }
            }
            scinfo.Sort((l, r) => (int)(l.Item1 - r.Item1));
            foreach (var s in scinfo)
                WriteLine(s.Item4);
            Out.Flush();
        }
    }
}