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.*;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;



public class Main{
	static int N,M;
	static int[] List;
	static int[][] city;
	static int[] Answer;
	
	public static class City implements Comparable<City> {
	    private int Pi;
	    private int Yi;
	    private int Count;
	    private int Flag;

	    public City(int Pi, int Yi, int Count, int Flag) {
	        this.Pi = Pi;
	        this.Yi = Yi;
	        this.Count=Count;
	        this.Flag = Flag;
	    }
	    @Override
	    public int compareTo(City o) {
	        return this.Yi - o.Yi;        
	    }
	    
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner ss = new Scanner(System.in);
		N = ss.nextInt();
		M = ss.nextInt();
		List = new int[N+1];
		city = new int[M][4];
		java.util.List<City> list =new ArrayList<>();
		for (int i = 0; i < M; i++) {
			city[i][0] = ss.nextInt();
			city[i][1] = ss.nextInt();	
			city[i][2] = 1;
			city[i][3] =i;
			list.add(new City(city[i][0], city[i][1], city[i][2], city[i][3]));
		}
		Collections.sort(list);
		
		for (int i = 0; i < M; i++) {
			City c = list.get(i);
			Object p = c.Pi;
			Object cnt = c.Count;
			int n = Integer.parseInt(p.toString());
			List[n]++;
			list.set(i, new City(c.Pi, c.Yi, List[n], c.Flag));
		}
		Collections.sort(list, new Comparator<City>() {
		    @Override
		    public int compare(City o1, City o2) {
		        return o1.Flag - o2.Flag;
		    }
		});
		for (int i = 0; i < M; i++) {
			City out = list.get(i);
			Object out_1 = out.Pi;
			Object out_2 = out.Count;
			String aa = out_1.toString();
			int len = aa.length();
			int n = 6-len;
			for (int j = 0; j < n; j++) {
				System.out.print("0");
			}
			System.out.print(out_1);
			String bb = out_2.toString();
			int len1 = bb.length();
			int n1 = 6-len1;
			for (int j = 0; j < n1; j++) {
				System.out.print("0");
			}
			System.out.print(out_2);
			System.out.println();

		}
		
	}

}