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.Text;
using System.Collections.Generic; 
using System.Linq; 
using E = System.Linq.Enumerable; 


class Program {
    //最短ステップ記録用
   
    static void Main(string[] args) {
        //入力を受け取る
        var NM = Console.ReadLine().Split().Select(a => int.Parse(a)).ToArray();
        var N  = NM[0];
        var M  = NM[1];
        
        //県ごとに市の情報を管理する
        var city = new List<long>[N+1];
        var ww = new long[M][];
        for(int i = 0;i <= N ;i++){
            city[i] = new List<long>();
        }
        for(int i = 0;i < M ;i++){
            var PY = Console.ReadLine().Split().Select(a => int.Parse(a)).ToArray();
            var P  = PY[0];
            var Y  = PY[1];
            city[P].Add(Y);
            ww[i]  = new long[2]{P,Y};
        }

        var dic = new Dictionary<long,int>[N+1];
        //県ごとに市の順位を求めていく
        var rank = new long[N+1][];
        for(int i = 1;i <= N ;i++){
            rank[i] = city[i].ToArray();
            Array.Sort(rank[i]);
　　　　　　dic[i] = new Dictionary<long,int>();
            for(int j = 0;j < rank[i].Length;j++){
		dic[i].Add(rank[i][j],j);
            }
        }
        

        
        //市ごとに順位情報を出力
        for(int i = 0;i < M ;i++){
            var PR = ww[i][0];
            var RA = dic[PR][ww[i][1]]+1;
           var tmp = string.Format($"{PR:000000}"); Console.WriteLine(tmp+string.Format($"{RA:000000}")); 
            
        }
      
     }
}