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.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	
	public static void main(String[] args){
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] p = new int[m];
		int[] year = new int[m];
		StringBuilder[] y = new StringBuilder[m];
		
		for(int i = 0; i < m; ++i) {
			p[i] = sc.nextInt() - 1;
			year[i] = sc.nextInt();
			if(y[p[i]] == null) {
				y[p[i]] = new StringBuilder(String.valueOf(year[i]));
			}else{
				y[p[i]].append(':');
				y[p[i]].append(year[i]);
			}
		}
		
		String[][] ystr = new String[m][];
		for(int i = 0; i < m; ++i) {
			if(y[i] != null) {
				ystr[i] = y[i].toString().split(":");
				Arrays.sort(ystr[i]);
				y[i] = null;
			}
		}
		
		for(int i = 0; i < m; ++i) {
			String key = String.valueOf(year[i]);
			int index = Arrays.binarySearch(ystr[p[i]], key) + 1;
			System.out.printf("%06d%06d\n", p[i] + 1, index);
		}
	}
}