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 = Integer.parseInt(sc.next());
        int m = Integer.parseInt(sc.next());
        int[] p = new int[m];
        int[] y = new int[m];
        //Map<Integer, Integer> ymap = new HashMap<>();
        Map<Integer, Integer> map = new TreeMap<>();
        for(int i=0; i<m; i++) {
            p[i] = Integer.parseInt(sc.next());
            y[i] = Integer.parseInt(sc.next());
            //ymap.put(y[i], p[i]);
            map.put(y[i], i);
        }

        int[] num = new int[m];
        int[] parr = new int[n];
        /*
        for(int key : map.keySet()) {
            int pre = ymap.get(key);
            parr[pre-1]++;
            num[map.get(key)] = parr[pre-1];
        }
        */
        for(int key : map.keySet()) {
            int pre = p[map.get(key)];
            parr[pre-1]++;
            num[map.get(key)] = parr[pre-1];
        }
        
        for(int i=0; i<m; i++) {
            String s = String.format("%06d", p[i])+String.format("%06d", num[i]);
            System.out.println(s);
        }
    }
}