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: Runtime Error)

import java.util.Scanner;
import java.util.Arrays;


class Main {
	
	public static class cityname {
		int location = 0;
		int year = 0;
	}
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int M = scan.nextInt();
					
		cityname[] city = new cityname[M];
		int[][] order  = new int[N][M];
		int[] order_index = new int[N];
		
		for (int i = 0; i < M ;i++){
			city[i] =  new cityname();
			city[i].location = scan.nextInt()-1;
			city[i].year = scan.nextInt();
			order[city[i].location][order_index[city[i].location]] = city[i].year;
			order_index[city[i].location]++;
		}
		
		for (int i = 0; i < N ;i++){
			if (order_index[city[i].location] != 0){
				Arrays.sort(order[i]);
			}
		}
		
		for  (int i = 0; i < M ;i++){
	
			for (int j=0; j < order_index[city[i].location];j++){
				if (city[i].year == order[city[i].location][M-j-1]){
					System.out.println(String.format("%06d", city[i].location+1)+String.format("%06d", order_index[city[i].location] - j));
					break;
				}	
			}

		}
	}
}