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: Accepted)



import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Scanner;

class City implements Comparable<City>{
    int p;
    int y;
    String id;

    City(int p, int y) {
        this.p = p;
        this.y = y;
    }

	@Override
	public int compareTo(City o) {
		return this.y - o.y;
	}

    
}

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();

        HashMap<Integer, ArrayList<City>> map = new HashMap<Integer, ArrayList<City>>();
        ArrayList<City> ansList = new ArrayList<City>();

        for (int i = 0; i < M; i++ ) {
            int p = sc.nextInt();
            int y = sc.nextInt();
            City c = new City(p, y);
            map.putIfAbsent(p, new ArrayList<City>());
            map.get(p).add(c);
            ansList.add(c);
        }

        for (int i = 0; i <= N; i++ ) {
            if (map.containsKey(i)) {
                ArrayList<City> list = map.get(i);
                list.sort(Comparator.naturalOrder());
                for (int j = 0; j < list.size(); j++ ) {
                    list.get(j).id = String.format("%06d%06d", i, j + 1);
                }
            }
        }

        ansList.stream().forEach(c -> System.out.println(c.id));

        sc.close();
    }

}