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: Runtime Error)

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {
	static int N,M;
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		N = sc.nextInt();
		M = sc.nextInt();
		City[] cityArr = new City[M];
		
		for(int i=0;i<M;i++) {
			int P = sc.nextInt();
			int Y = sc.nextInt();
			cityArr[i] = new City(P,Y,i);
		}
		Arrays.sort(cityArr,new Comparator<City>() {
			@Override
			public int compare(City o1, City o2) {
				// TODO Auto-generated method stub
				if(o1.xq>=o2.xq) {
					if(o1.year>=o2.year) {
						return 1;
					}else {
						return -1;
					}
				}else {
					return -1;
				}
			}
		});
		
		int sort = 0;
		City c = null;
		for(int i=0;i<cityArr.length;i++) {
			c = cityArr[i];
			if(i > 0 && cityArr[i].xq != cityArr[i-1].xq) {
				sort = 0;
			}
			sort++;
			String id = String.format("%06d", c.xq) + String.format("%06d", sort);
			c.id = id;
		}
		
		Arrays.sort(cityArr,new Comparator<City>() {
			@Override
			public int compare(City o1, City o2) {
				// TODO Auto-generated method stub
				if(o1.index>o2.index) {
					return 1;
				}else {
					return -1;
				}
			}
		});
		
		for(int i=0;i<cityArr.length;i++) {
			System.out.println(cityArr[i].id);
		}
	}
	
	public static class City{
		public int xq,year,index;
		public String id;

		public City(int xq, int year, int index) {
			super();
			this.xq = xq;
			this.year = year;
			this.index = index;
		}
	}

}