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.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] p = new int[m];
        int[] y = new int[m];
        int[] id = new int[m];
        for (int i = 0; i < m; i++) {
            p[i] = sc.nextInt();
            y[i] = sc.nextInt();
            id[i] = p[i] * 1000000;
        }
        for (int nn = 0; nn < n; nn++) {
            ArrayList<Integer> year = new ArrayList<>();
            Map<Integer, Integer> key = new HashMap<>();
            for (int i = 0; i < m; i++) {
                if (p[i] - 1 == nn) {
                    year.add(y[i]);
                    key.put(y[i], i);
                }
            }
            Collections.sort(year);
            if (year.size() != 0) {
                for (int i = 0; i < year.size(); i++) {
                    if (p[key.get(year.get(i))] - 1 == nn) id[key.get(year.get(i))] += (i + 1);
                }
            }
        }
        for (int i = 0; i < m; i++) {
            System.out.println(String.format("%012d", id[i]));
        }
    }
}