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.*;

/**
 * year -> orderの変換を作る
 * 
 * @author glycine
 *
 */
public class Main {
	private static class Node {
		int p;
		long y;
		int order = -1;

		public Node(int p, long y) {
			this.p = p;
			this.y = y;
		}
	}

	int N, M;
	int[] indexes;
	List<Node> nodes;
	Map<Long, Node> maps = new TreeMap<>();
	List<String> results;

	public Main() {
		Scanner in = new Scanner(System.in);
		N = in.nextInt();
		M = in.nextInt();
		indexes = new int[N];
		Arrays.fill(indexes, 0);
		nodes = new ArrayList<>(M);
		for (int i = 0; i < M; ++i) {
			int p = in.nextInt();
			long y = in.nextLong();
			Node node = new Node(p, y);
			nodes.add(node);
			maps.put(node.y, node);
		}
		in.close();
	}

	private void calc() {
		for (Node city : maps.values()) {
			int i = city.p - 1;
			++indexes[i];
			city.order = indexes[i];
		}
	}

	private void show() {
		for (int i = 0; i < nodes.size(); ++i) {
			Node node = nodes.get(i);
			int p = node.p;
			int order = node.order;
			String line = String.format("%06d%06d", p, order);
			System.out.println(line);
		}
	}

	public static void main(String[] args) {
		Main ins = new Main();
		ins.calc();
		ins.show();
	}
}