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.*;
import java.util.Map.*;

class Main{
	static Scanner s=new Scanner(System.in);
	public static void main(String[] $){
		int n=s.nextInt(),m=s.nextInt();
		int[]p=new int[m];
		int[]y=new int[m];
		String[]r=new String[m];
		HashMap<Integer,TreeMap<Integer,Integer>>map=new HashMap<>();
		for(int q=0;q<m;++q) {
			p[q]=s.nextInt();
			y[q]=s.nextInt();
			map.computeIfAbsent(p[q],i->new TreeMap<>()).put(y[q],q);
		}
		for(Entry<Integer,TreeMap<Integer,Integer>> e:map.entrySet()) {
			int no=0;
			for(Entry<Integer,Integer>f:e.getValue().entrySet()) {
				r[f.getValue()]=String.format("%06d%06d",e.getKey(),++no);
			}
		}
		Arrays.stream(r).forEach(System.out::println);
	}
}