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 static java.lang.System.*;

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

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] numberA = new int[m];
		int[] numberB = new int[m];
		List<City> cities = new ArrayList<>();
		for(int i = 0; i < m; i++) {
			City city = new City(i, sc.nextInt(), sc.nextInt());
			cities.add(city);
		}
		Collections.sort(cities);
		
		int currentKen = -1;
		int cnt = 1;
		for(int i = 0; i < cities.size(); i++) {
			City city = cities.get(i);
			numberA[city.num] = city.ken;
			if (city.ken != currentKen) {
				currentKen = city.ken;
				cnt = 1;
			} else {
				cnt++;
			}
			numberB[city.num] = cnt;
		}
		for(int i = 0; i < m; i++) {
			out.println(String.format(
					"%06d%06d", numberA[i], numberB[i]));
		
			
		}
		
	}
	
	
	static class City implements Comparable<City>{
		int num;
		Integer ken;
		Integer year;
		
		City(int num, int ken, int year){
			this.num = num;
			this.ken = ken;
			this.year = year;
		}

		@Override
		public int compareTo(City o) {
			
			int res = this.ken.compareTo(o.ken);
			if (res != 0)
				return res;
			else {
				return this.year.compareTo(o.year);
			}
		}
	}
	

}