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.LinkedHashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
public class Main {
        static int  PRE,CITY ;
        public static void main (String args[]) throws Exception{
            Scanner sc = new Scanner(System.in);
            PRE = sc.nextInt();
            CITY = sc.nextInt();
            Map<Integer,Integer>  inputMap = new LinkedHashMap<>();
            TreeMap<Integer, LinkedList<Integer>>  treeMap = new TreeMap<>();
            for(int i = 0; i<CITY; i++){
            	int a = sc.nextInt();
            	int b = sc.nextInt();
            	inputMap.put(b, a);
            	if (!treeMap.containsKey(a)) {
            		LinkedList<Integer> linkedList = new LinkedList<>();
            		linkedList.add(b);
            		treeMap.put(a, linkedList);
				}else {
					treeMap.get(a).add(b);
				}
            }
            for (Integer key : treeMap.keySet()) {
            	Collections.sort(treeMap.get(key));
			}
            for (Map.Entry<Integer, Integer> entry : inputMap.entrySet()) {
            	 String p = String.format("%06d", entry.getValue());
            	 String c = String.format("%06d", treeMap.get(entry.getValue()).indexOf(entry.getKey())+1);
                 System.out.println(p+""+c);
            }
            sc.close();
        }
    }