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.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;

class Main
{
    public static String getId(int p, int x) {
        return String.format("%06d", p) + String.format("%06d", x);
    }
    
    public static void main(String args[])
    {
        class Io {
            public BufferedReader br;

            public Io() {
                InputStreamReader ir = new InputStreamReader(System.in);
                this.br = new BufferedReader(ir);
            }
            
            public ArrayList<Integer> inputInts() {
                String[] inputParts = {""};
        
                try { 
                    inputParts = br.readLine().split(" ");
                }
                catch (IOException e) {
                    System.out.println("Error " + e.getMessage());
                    e.printStackTrace();
                }

                int n = inputParts.length;
                ArrayList<Integer> ints = new ArrayList<>();
                for (int i = 0; i < n; i++) {
                    ints.add(Integer.valueOf(inputParts[i]));
                }
                return ints;
            }
        }

        Io io = new Io();
        ArrayList<Integer> ints = io.inputInts();
        int N = ints.get(0), M = ints.get(1);
        HashMap<Integer, ArrayList<Integer>> prefs = new HashMap<>();
        HashMap<Integer, ArrayList<Integer>> cities = new HashMap<>();

        for (int i = 1; i <= N; i++) {
            prefs.put(i, new ArrayList<Integer>());
        }

        for (int i = 1; i <= M; i++) {
            ints = io.inputInts();
            int p = ints.get(0), y = ints.get(1);
            prefs.get(p).add(i);
            ArrayList<Integer> attrs = new ArrayList<>(3);
            attrs.add(p);
            attrs.add(y);
            cities.put(i, attrs);
        }

        for (int i = 1; i <= N; i++) {
            if (prefs.get(i).size() > 1) {
                prefs.get(i).sort((Integer city_a, Integer city_b) -> cities.get(city_a).get(1) - cities.get(city_b).get(1));
            }
        }

        for (int i = 1; i <= N; i++) {
            int size = prefs.get(i).size();
            for (int j = 0; j < size; j++) {
                cities.get(prefs.get(i).get(j)).add(j + 1);
            }
        }

        PrintWriter pw = new PrintWriter(System.out);
        for (int i = 1; i <= M; i++) {
            ArrayList<Integer> city = cities.get(i);
            pw.println(getId(city.get(0), city.get(2)));
        }
        pw.flush();
    }
}