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;

namespace ABC113_C{
    struct P{
        public int city;
        public int year;
        public P(int city,int year){
            this.city = city;
            this.year = year;
        }
    }
    class Program{
        static void Main(string[] args){
            var line = Console.ReadLine().Split(' ');
            var N = int.Parse(line[0]);
            var M = int.Parse(line[1]);
            var list = new List<P>();
            var numbers = new int[M];

            for(var i = 0;i < M;i++){
                var input = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
                list.Add(new P(input[0],input[1]));
            }
            
            var list2 = list.OrderBy(x => x.city).ThenBy(x => x.year).ToArray();
            
            var temp = list2[0].city;
            var numTemp = 1;
            numbers[0] = numTemp;

            for(var i = 1;i < M;i++){
                if(temp == list2[i].city){
                    numbers[i] = ++numTemp;
                }else{
                    numTemp = 1;
                    numbers[i] = numTemp;
                    temp = list2[i].city;
                    
                }
            }

            for(var i = 0;i < M;i++){
                Console.WriteLine($"{list2[i].city:D6}{numbers[i]:D6}");
            }




        }
    }
}