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: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;

public class Main{
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] inStr = br.readLine().split(" ");
        int N = Integer.parseInt(inStr[0]);
        int M = Integer.parseInt(inStr[1]);
        int n = 100000;
        String[] arrSort = new String[M];
        int[][] arr = new int[M][2];
        for (int i = 0; i < M; i++) {
            inStr = br.readLine().split(" ");
            arrSort[i] = (n + Integer.parseInt(inStr[0])) + "" + (n + Integer.parseInt(inStr[1]));
            arr[i][0] = Integer.parseInt(inStr[0]);
            arr[i][1] = Integer.parseInt(inStr[1]);
        }
        Arrays.sort(arrSort);
        Map<Integer, List<Integer>> map = new HashMap<>();
        for (int i = 0; i < M; i++) {
            int key = Integer.parseInt(arrSort[i].substring(0, 6)) - n;
            int value = Integer.parseInt(arrSort[i].substring(6, 12)) - n;
            if (map.containsKey(key)) {
                map.get(key).add(value);
            } else {
                List<Integer> list = new ArrayList<>();
                list.add(value);
                map.put(key, list);
            }
        }
        for (int i = 0; i < M; i++) {
            System.out.println(String.format("%06d", (arr[i][0])) + String.format("%06d", (map.get(arr[i][0]).indexOf(arr[i][1]) + 1)));
        }
    }

    private static String getId(int num) {
        String str = String.valueOf(num);
        String pNum = "";
        if (str.length() < 6) {
            for (int i = 0; i < 6 - str.length(); i++) {
                pNum += "0";
            }
            pNum += str;
        } else {
            pNum = str;
        }
        return pNum;
    }
}