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.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {

	public static void main(String[] args) throws IOException {
//		System.setIn(new FileInputStream("tc/1.txt"));
		Scanner sc = new Scanner(System.in);
		sc.nextInt();
		int M = sc.nextInt();
		TreeMap<String, Integer> order = new TreeMap<>();
		ArrayList<CP> data = new ArrayList<>();
		for (int i = 0; i < M; i++) {
			int pref = sc.nextInt();
			int year = sc.nextInt();
			order.put(String.format("%07d",pref) + "_" + String.format("%10d",year), pref);
			data.add(new CP(year, pref));
		}

		int curPref = -1;
		int count = 0;
		for (String key : order.keySet()) {
			int pref = order.get(key);
			if (curPref == -1 || pref != curPref) {
				curPref = pref;
				count = 0;
			}
			count++;
			order.put(key, count);
		}

		for (int i = 0; i < data.size(); i++) {
			CP a = data.get(i);
			int pref = a.pref;
			int year = a.year;
			int yRank = order.get(String.format("%07d",pref) + "_" + String.format("%10d",year));
			String result = String.format("%06d%06d", pref, yRank);
			System.out.println(result);
		}
		sc.close();
	}

	static class CP {
		int year;
		int pref;

		public CP(int year, int pref) {
			super();
			this.year = year;
			this.pref = pref;
		}
	}

}