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.*;
import java.io.*;

public class Main {

  public static void main (String[] args) {

    Scanner sc = new Scanner(System.in);

    int N = Integer.parseInt(sc.next());;
    int M = Integer.parseInt(sc.next());;
    int[][] P = new int[M][4];
    
    for (int i = 0; i < M; i++) {
      P[i][0] = i;
      P[i][1] = Integer.parseInt(sc.next());;
      P[i][2] = Integer.parseInt(sc.next());;
      P[i][3] = 0; 
    }

    sc.close();

    Arrays.sort(P, (o1, o2) -> o1[1] == o2[1] ? o1[2] - o2[2] : o1[1] - o2[1]);

    
    int now = P[0][1];
    int count = 0;

    for (int i = 0; i < M; i++) {
      if (now == P[i][1]) {
        count++;
      } else {
        count = 1;
        now = P[i][1];
      }
      P[i][3] = count;
    }

    Arrays.sort(P, (a, b) -> Integer.compare(a[0],b[0]));

    PrintWriter out = new PrintWriter(System.out);
    for (int i = 0; i < M; i++) {
      out.println(String.format("%06d", P[i][1]) + String.format("%06d", P[i][3]));
    }
    out.flush();

  }

}