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: Time Limit Exceeded)


using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace MyProgram
{
    public class Pref
    {
        internal List<int> cityBirth;
        internal int number;
        
        public Pref()
        {
            number = -1;
            cityBirth = new List<int>();
        }
    }
    
    public class Program
    {	
        public static void Main(string[] args)
        {
            int[] n = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
            int N = n[0];
            int M = n[1];
            int P = 0;
            int Y = 0;
            
            Pref[] prefs = new Pref[N];
            for(int i = 0 ; i < N ; i++)
            {
                prefs[i] = new Pref();
                prefs[i].number = i+1;
            }
            
            List<string> list = new List<string>();
            string[] input;
            for(int i = 0 ; i < M ; i++)
            {
                list.Add(Console.ReadLine());
                input = list[list.Count-1].Split(' ');
            
                P = int.Parse(input[0]);
                Y = int.Parse(input[1]);
                
                prefs[P-1].cityBirth.Add(Y);
            }
            
            for(int i = 0 ; i < N ;i++)
            {
                prefs[i].cityBirth.Sort();
            }
            
            string[] buf;
            int ap,ay;
            string sp, si;
            for(int i = 0 ; i < list.Count ; i++)
            {
                buf = list[i].Split(' ');
                ap = int.Parse(buf[0]);
                int index = prefs[ap-1].cityBirth.IndexOf(int.Parse(buf[1])) +1;
                sp = ap.ToString();
                si = index.ToString();
                sp = sp.PadLeft(6,'0');
                si = si.PadLeft(6,'0');
                Console.WriteLine(sp+si);
            }
        }
    }
}