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.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Main{

	public static void main(String args[]){

		Scanner sc = new Scanner(System.in);

		int n=sc.nextInt();
		int m=sc.nextInt();
		int p[]= new int[m];
		long y[]=new long[m];
		HashMap<Long,Long> map= new HashMap<Long,Long>();
;		long num[]=new long[m];

		for(int i=0;i<m;++i){
			p[i]=sc.nextInt();
			y[i]=sc.nextLong();
			num[i]=10000000000L*p[i]+y[i];
		}
		Arrays.sort(num);

		long div=1;
		long counter=1;
		for(int i=0;i<m;++i){
			if(num[i]/10000000000L==div);
			else{
				div=num[i]/10000000000L;
				counter=1;
			}
			map.put(num[i]-div*10000000000L,counter);
			++counter;
		}

		for( int i=0;i<m;++i){
			String s=String.valueOf((long)1000000+p[i]);
			String s2=String.valueOf(1000000+map.get(y[i]));
			System.out.println(s.substring(1)+s2.substring(1));
		}
	}
}