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.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

/**
 * https://abc113.contest.atcoder.jp/tasks/abc113_c
 */
public class Main {
    public static void main(String[] args) {
        try (Scanner in = new Scanner(System.in)) {
            solve(in);
        }
    }

    private static void solve(Scanner in) {
        int N = in.nextInt();
        int M = in.nextInt();
        List<Data> data = new ArrayList<>(M);
        for (int i = 0; i < M; i++) {
            data.add(i, new Data(in.nextInt(), in.nextInt(), 1, i));
        }
        Collections.sort(data, Data.BY_Y);
        Collections.sort(data, Data.BY_P);
        for (int i = 1; i < M; i++) {
            if (data.get(i).p == data.get(i - 1).p) {
                data.get(i).id = data.get(i - 1).id + 1;
            }
        }
        Collections.sort(data, Data.BY_ORIG);
        StringBuilder ans = new StringBuilder();
        for (int i = 0; i < M; i++) {
            // System.out.println(data.get(i).getAns()); TLE
            ans.append(data.get(i).getAns()).append("\n");
        }
        System.out.println(ans);
    }

    private static class Data {
        private int p, y, id, orig;
        private static final Comparator<Data> BY_P = (o1, o2) -> Integer.compare(o1.p, o2.p);
        private static final Comparator<Data> BY_Y = (o1, o2) -> Integer.compare(o1.y, o2.y);
        private static final Comparator<Data> BY_ORIG = (o1, o2) -> Integer.compare(o1.orig, o2.orig);

        private Data(int p, int y, int id, int orig) {
            this.p = p;
            this.y = y;
            this.id = id;
            this.orig = orig;
        }

        private String getAns() {
            return String.format("%06d%06d", p, id);
        }
    }
}