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 Java7 (OpenJDK 1.7.0) (judge verdict: Time Limit Exceeded)

import java.util.Arrays;
import java.util.Comparator;
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();
		sc.nextLine();
		int[][] arr = new int[m][4];
		for (int i = 0; i < m; i++) {
			arr[i][0] = sc.nextInt();
			arr[i][1] = sc.nextInt();
			arr[i][2] = i;
			sc.nextLine();
		}
		sort(arr,1);
		int[] count = new int[n+1];
		for(int i=0; i<m; i++){
			arr[i][3] = count[arr[i][0]]+1;
			count[arr[i][0]]++;
		}
		sort(arr,2);
		for(int i=0; i<m; i++){
			System.out.println(String.format("%06d", arr[i][0])+String.format("%06d", arr[i][3]));
		}
	}

	public static void sort(int[][] ob, final int order) {
		Arrays.sort(ob, new Comparator<Object>() {
			public int compare(Object o1, Object o2) {
				int[] one = (int[]) o1;
				int[] two = (int[]) o2;
				if (one[order] > two[order]) {
					return 1;
				} else if (one[order] < two[order]) {
					return -1;
				} else {
					return 0;
				}
			}
		});
	}

}