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

public class Main {
	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int m=scanner.nextInt();
		int p[]=new int[m];
		int y[]=new int[m];
		Map<Integer,List<Integer>>map=new TreeMap<>();
		for(int i=0;i<m;i++) {
			p[i]=scanner.nextInt();
			y[i]=scanner.nextInt();
			if (map.containsKey(p[i])) {
				map.get(p[i]).add(y[i]);
				//Collections.sort(map.get(p[i]));
			} else {
				List<Integer>list=new ArrayList<>();
				list.add(y[i]);
				map.put(p[i], list);
			}
		}
		for(List<Integer> list:map.values()) {
			Collections.sort(list);
		}
		for(int i=0;i<m;i++) {
			int ind=lower_bound(map.get(p[i]), y[i])+2;
			System.out.printf("%06d", p[i]);
			System.out.printf("%06d", ind);
			System.out.println("");
			
		}
	}
	private static int lower_bound(List<Integer> list, int val) {
		return ~Collections.binarySearch(list, val, (x, y) -> x.compareTo(y) >= 0 ? 1 : -1) - 1;
	}
}