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.*;

public class Main {

	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[][] cities = new int[m][3];//p, year, no
		int[][] sortedCities = new int[m][];
		for (int i = 0; i < m; i++) {
			cities[i][0] = sc.nextInt();
			cities[i][1] = sc.nextInt();
			sortedCities[i] = cities[i];
		}
		Arrays.sort(sortedCities, new Comparator<int[]>() {
		public int compare(int[] c1, int[] c2) {
			if (c1[0] != c2[0]) {
				return c1[0] - c2[0];
			} else {
				return c1[1] - c2[1];
			}
		}
		});
		int idx = 1;
		sortedCities[0][2] = idx;
		for (int i = 1; i < m; i++) {
			if (sortedCities[i - 1][0] == sortedCities[i][0]) {
				idx++;
			} else {
				idx = 1;
			}
			sortedCities[i][2] = idx;
		}
		for (int i = 0; i < m; i++) {
			System.out.print(String.format("%06d", cities[i][0]));
			System.out.println(String.format("%06d", cities[i][2]));
		}
		
	}
	
	
}