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.*;
 
public class Main{
  public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    String[] S = sc.nextLine().split(" ");
    int N = Integer.parseInt(S[0]);
    int M = Integer.parseInt(S[1]);
    
    int[][] val = new int[M][2];
    Map<Integer, List<Integer>> map = new HashMap<>();
    for(int i = 0; i < M; i++){
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      val[i][0] = a;
      val[i][1] = b;
      if(map.containsKey(a)){
        map.get(a).add(b);
      }else{
        map.put(a, new ArrayList<Integer>());
        map.get(a).add(b);
      }
    }
    
    for(int i = 1; i <= N; i++){
      Collections.sort(map.get(i));
    }
    
    for(int i = 0; i < M; i++){
      int a = val[i][0];
      int b = map.get(a).indexOf(val[i][1])+1;
      
      String s = String.format("%06d%06d", a, b);
      System.out.println(s);
    }
  }
}