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: Wrong Answer)

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int N = in.nextInt();
		int M = in.nextInt();
		
		List<CityVo> list = new ArrayList<CityVo>();
		for(int i=0; i < M; i++) {
			CityVo cityVo = new CityVo();
			cityVo.setIndex(String.valueOf(i));
			cityVo.setCity(String.valueOf(in.nextInt()));
			cityVo.setYear(String.valueOf(in.nextInt()));
			list.add(cityVo);
		}
		
		Set<String> citySet = new HashSet<String>();
		for (CityVo cityVo : list) {
			citySet.add(cityVo.getCity());
		}

		List<CityVo> list2 = new ArrayList<CityVo>();
		for (String tempCity : citySet) {
			List<CityVo> templist = new ArrayList<CityVo>();
			for (CityVo cityVo : list) {
				if(tempCity.equals(cityVo.getCity())) {
					templist.add(cityVo);
				}
			}
			Collections.sort(templist, new Comparator<CityVo>(){
	           
	            @Override
	            public int compare(CityVo o1, CityVo o2) {
	            	// TODO Auto-generated method stub
	            	return o1.getYear().compareTo(o2.getYear());
	            }
	        });
			
			for(int index = 1; index <= templist.size(); index++) {
				CityVo cityVo = templist.get(index-1);
				String city = String.valueOf((1000000 + Integer.parseInt(cityVo.getCity()))).substring(1);
				String year = String.valueOf(1000000 + index).substring(1);
				cityVo.setCity(city);
				cityVo.setYear(year);
				cityVo.setCityyear(city+year);
			}
			
			list2.addAll(templist);
		}
		
		if(list2.size() > 0) {
			Collections.sort(list2, new Comparator<CityVo>(){
		           
	            @Override
	            public int compare(CityVo o1, CityVo o2) {
	            	// TODO Auto-generated method stub
	            	return o1.getIndex().compareTo(o2.getIndex());
	            }
	        });
		}
		for (CityVo cityVo : list2) {
			System.out.println(cityVo.getCityyear());
		}
	}
}


class CityVo {
	String index;
	String city;
	String year;
	String cityyear;
	public String getIndex() {
		return index;
	}
	public void setIndex(String index) {
		this.index = index;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getYear() {
		return year;
	}
	public void setYear(String year) {
		this.year = year;
	}
	
	public String getCityyear() {
		return cityyear;
	}
	public void setCityyear(String cityyear) {
		this.cityyear = cityyear;
	}
	@Override
	public String toString() {
		return "CityVo [index=" + index + ", city=" + city + ", year=" + year + ", cityyear=" + cityyear + "]";
	}
	
	
}