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.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeSet;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int areas = sc.nextInt();
		int citys = sc.nextInt();
		List<Integer> area= new ArrayList<Integer>();
		List<Integer> cityTimes= new ArrayList<Integer>();
		Map<String,TreeSet<Integer>> map = new HashMap<>();
		int temp=0;
		String key = "";
		String str="";
		List<String> areasList = new ArrayList<String>();
		TreeSet<Integer> set =null;
		for (int i = 0; i < citys; i++) {
			area.add(sc.nextInt());
			cityTimes.add(sc.nextInt());
			str = ""+area.get(i);
			switch(str.length()){
			case 1:
				areasList.add("00000"+str);
				break;
			case 2:
				areasList.add("0000"+str);
				break;
			case 3:
				areasList.add("000"+str);
				break;
			case 4:
				areasList.add("00"+str);
				break;
			case 5:
				areasList.add("0"+str);
				break;
			case 6:
				areasList.add(""+str);
				break;
			}
			key = areasList.get(i);
			if(!map.containsKey(key)){
				set = new TreeSet<Integer>();
				set.add(cityTimes.get(i));
				map.put(key, set);
			}else{
				map.get(key).add(cityTimes.get(i));
			}
		}
		for (int i = 0; i < area.size(); i++) {
			key = areasList.get(i);
			temp = new ArrayList(map.get(key)).indexOf(cityTimes.get(i))+1;
			System.out.println(key+String.format("%06d", temp));
		}
		sc.close();
	}
}