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.util.Collections;
import java.util.LinkedList;
import java.util.Scanner;
public class Main {
        static int  PRE,CITY ;
        static int arr[][];
        public static void main (String args[]) throws Exception{
            Scanner sc = new Scanner(System.in);
            PRE = sc.nextInt();
            CITY = sc.nextInt();
            arr = new int[CITY][2];
            LinkedList<Integer> list = new LinkedList<>();
            for(int i = 0; i<CITY; i++){
            	arr[i][0]= sc.nextInt();
            	arr[i][1] = sc.nextInt();
            	if (!list.contains(arr[i][0])) {
					list.add(arr[i][0]);
				}
            }
            LinkedList<Integer> tempList = new LinkedList<Integer>();
            LinkedList<Integer> tempIndexList = new LinkedList<Integer>();
            for(int t = 0; t<list.size(); t++){
	            tempList.clear(); 
	            tempIndexList.clear();
	            for(int j = 0;j<arr.length;j++){
	            	if (arr[j][0] == list.get(t)) {
	            		tempList.add(arr[j][1]); 
	            		tempIndexList.add(j);
					}
	            }
	            Collections.sort(tempList);
	            for(int j = 0;j<tempIndexList.size();j++){
	            	arr[tempIndexList.get(j)][1] = tempList.indexOf(arr[tempIndexList.get(j)][1])+1;
	            }
            }
            for (int i = 0; i < arr.length; i++) {
            	 String p = String.format("%6s", arr[i][0]);
            	 String c = String.format("%6s", arr[i][1]);
                 p = p.replaceAll("\\s","0");
                 c = c.replaceAll("\\s","0");
                 System.out.println(p+""+c);
			}
            sc.close();
        }
        
    }