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: Wrong Answer)

import java.util.*;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int prefectureNum = sc.nextInt();
		int cityNum = sc.nextInt();
		Map<String, List<String>> map = new HashMap<String, List<String>>();
		
		for(int i = 0; i < prefectureNum; i++){
			map.put(String.valueOf(i+1), new ArrayList<String>());
		}
		for(int i = 0; i < cityNum; i++){
            String hoge = sc.next();
            String fuga = sc.next();
			map.get(hoge).add(fuga);
		}
		
		for(String key : map.keySet()){
			Collections.sort(map.get(key));
			for(int i = 0; i < map.get(key).size(); i++){
				String keyAns = key;
				while(keyAns.length() <= 6){
					keyAns = "0" + keyAns;
				}
				String valAns = String.valueOf(i);
				while(valAns.length() <= 6) {
					valAns = "0" + valAns;
				}
				System.out.println(keyAns + valAns);
			}
		}
	}
}