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.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int N = in.nextInt();
		int M = in.nextInt();
		int[] P = new int[M];
		Long[] Y = new Long[M];
		for (int i = 0; i < M; i++) {
			P[i] = in.nextInt() - 1;
			Y[i] = in.nextLong();
		}
		ArrayList<ArrayList<Long>> vals = new ArrayList<ArrayList<Long>>() {
			{
				for (int i = 0; i < N; i++) {
					add(new ArrayList<Long>());
				}
			}
		};
		for (int i = 0; i < M; i++) {
			vals.get(P[i]).add(Y[i]);
		}
		for (int i = 0; i < N; i++) {
			Collections.sort(vals.get(i));
		}
		for (int i = 0; i < M; i++) {
			int v = P[i];
			System.out.print(String.format("%06d", v + 1));
			int id = Collections.binarySearch(vals.get(v), Y[i]);
			System.out.print(String.format("%06d\n", id + 1));
		}
		in.close();
	}
}