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 Java (OpenJDK 11.0.6) (judge verdict: Runtime Error)

import java.util.Scanner;
import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
 
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+1];
    long[] Y = new long[M+1];
    int[] num = new int[M+1];
    int[] sum = new int[100001];
    int[] count = new int[10001];
    List<Long> Ylist = new ArrayList<Long>();
    for (int i =1; i<M+1; i++) {
      int a = sc.nextInt();
      long b = sc.nextLong();
      P[i] = a;
      Y[i] = a * 100000 + b;
      count[a]++;
      Ylist.add(a * 100000 + b);
    }
    Collections.sort(Ylist);
    for (int i =1; i<M+1; i++) {
      num[i] = Ylist.indexOf(Y[i]) + 1;
    }
    for (int i =1; i<M+1; i++) {
      for (int j =1; j<i; j++) {
        sum[i] += count[j];
      }
    }
    for (int i =1; i<M+1; i++) {
      num[i] = num[i] - sum[P[i]];
      System.out.println(String.format("%06d",P[i]) + String.format("%06d",num[i]));
    }
  } 
}