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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class Main {
	

	
	public static void main(String[] args) {

		try (Scanner sc = new Scanner(System.in)) {
			int N = sc.nextInt();
			int M = sc.nextInt();
			List<Model> list = new ArrayList<>();
			for (int i = 1; i <= M; i++) {
				int P = sc.nextInt();
				int Y = sc.nextInt();
				Model model = new Model(i, P, Y);
				list.add(model);
			}
			
			list.sort(Comparator.comparing(Model::getKen).thenComparing(Model::getYear));
			
			int kenCount = 0;
			int yearCount = 0;
			for (Model m : list) {
				if(m.getKen() != kenCount) {
					kenCount = m.getKen();
					yearCount = 1;
				}
				m.setMoji(kenCount, yearCount);
				yearCount++;
			}
			list.sort(Comparator.comparing(Model::getIndex));
			list.forEach(m -> System.out.println(m.getMoji()));
		} // Scanner Close
	}
}

 class Model {
	public int index;
	public int ken;
	public int year;
	public String moji;
	public Model(int index, int ken, int year) {
		this.index = index;
		this.ken = ken;
		this.year = year;
	}
	public int getIndex() {
		return this.index;
	}
	public int getKen() {
		return this.ken;
	}
	public int getYear() {
		return this.year;
	}
	public void setMoji(int ken, int year) {
		String kenMoji = String.format("%06d", ken);
		String yearMoji = String.format("%06d", year);
		StringBuffer sb = new StringBuffer();
		this.moji = sb.append(kenMoji).append(yearMoji).toString();
	}
	public String getMoji() {
		return this.moji;
	}
}