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.*;

public class Main{
    
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int M = sc.nextInt();
        int[][] Y = new int[2][M];
        
        for(int i = 0; i < M; i++){
            Y[0][i] = sc.nextInt();
            Y[1][i] = sc.nextInt();
        }
        sc.close();
        int[] index  = new int[M];
        for(int i = 0; i < M; i++)
            index[i] = i;
        HashMap<Integer, Integer> map = new HashMap<>();
        for(int i = 0; i < M; i++){
            map.put(Y[1][i], index[i]);
        }
        Arrays.sort(Y[1]);
        int[] count = new int[N];
        for(int i = 0; i < N; i++)
            count[i] = 1;
        int[] countM = new int[M];
        for(int i = 0; i < M; i++){
            countM[map.get(Y[1][i])] = count[Y[0][map.get(Y[1][i])] -1];
            count[Y[0][map.get(Y[1][i])] -1]++;
        }
        for(int i = 0; i < M; i++){
            System.out.println(String.format("%06d%06d", Y[0][i], countM[i]));
        }
    }
}