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.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		
		int N = sc.nextInt();
		int M = sc.nextInt();
		List<TreeMap> mapList = new ArrayList<TreeMap>();
		int[][] valAry = new int[M][2];
		
		for(int i = 0; i < N ; i++){
			TreeMap<Integer, Integer> map = new TreeMap<Integer, Integer>();
			mapList.add(map);
		}
		for(int i = 0; i < M ; i++){
			int P = sc.nextInt();
			int Y = sc.nextInt();
			mapList.get(P-1).put(Y, i);
			valAry[i][0] = P;
			valAry[i][1] = Y;
		}
		for(Map map : mapList){
			Iterator<Map.Entry<Object, Object>> it = map.entrySet().iterator();
			int i = 1;
			while (it.hasNext()) {
				Map.Entry<Object, Object> entry = it.next();
				entry.setValue(i);
				i++;
			}
		}
		for(int i = 0; i < M ; i++){
			System.out.println(String.format("%06d", valAry[i][0])+String.format("%06d", mapList.get(valAry[i][0]-1).get(valAry[i][1])));
		}
	}
}