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 {

    void run() {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), m = sc.nextInt();
        HashMap<Integer, ArrayList<V>> input = new HashMap<>();

        for (int i = 0; i < m; i++) {
            int p = sc.nextInt(), y = sc.nextInt();
            if (input.containsKey(p)) {
                ArrayList<V> l = input.get(p);
                l.add(new V(i, y));
            } else {
                ArrayList<V> l = new ArrayList<>();
                l.add(new V(i, y));
                input.put(p, l);
            }
        }

        PriorityQueue<V> q = new PriorityQueue<>(Comparator.comparingInt(o -> o.idx));

        for (Map.Entry<Integer, ArrayList<V>> entry: input.entrySet()) {
            ArrayList<V> l = entry.getValue();
            Collections.sort(l, Comparator.comparingLong(o -> o.y));
            int i = 1;
            for (V v: l) {
                v.y = entry.getKey() * 1000000 + i;
                q.add(v);
                i++;
            }
        }
        for (;!q.isEmpty();) {
            V v = q.remove();
            System.out.println(String.format(String.format("%012d", v.y)));
        }
    }

    class V {

        int idx;
        long y;
        V(int idx, long y) {
            this.idx = idx;
            this.y = y;
        }
    }

    public static void main(String[] args) {
        new Main().run();
    }
}