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: Time Limit Exceeded)

import java.util.*;

class Pair implements Comparable {
    int p;
    int y;
    int shiIdx;

    Pair(int p, int y, int shiIdx) {
        this.p = p;
        this.y = y;
        this.shiIdx = shiIdx;
    }

    @Override
    public int compareTo(Object o) {
        Pair other = (Pair) o;
        return this.y - other.y;
    }
}

class Pair2 implements Comparable {
    int shiIdx;
    String id;

    Pair2(int shiIdx, String id) {
        this.shiIdx = shiIdx;
        this.id = id;
    }

    @Override
    public int compareTo(Object o) {
        Pair2 other = (Pair2) o;
        return this.shiIdx - other.shiIdx;
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();

        Pair[] pairs = new Pair[M];
        for (int i = 0; i < M; i++) {
            int p = sc.nextInt();
            int y = sc.nextInt();
            pairs[i] = new Pair(p, y, i);
        }

        Arrays.sort(pairs);

        Map<Integer, Integer> map = new HashMap<>();
        Pair2[] pairs2 = new Pair2[M];

        for (int i = 0; i < M; i++) {
            Pair pair = pairs[i];
            int num;
            if (!map.containsKey(pair.p)) {
                map.put(pair.p, 1);
                num = 1;
            } else {
                num = map.get(pair.p) + 1;
                map.put(pair.p, num);
            }

            // pair.pを6桁に変換 + numを6桁に変換 = id
            Pair2 pair2 = new Pair2(pair.shiIdx, String.format("%06d", pair.p) + String.format("%06d", num));
            pairs2[pair.shiIdx] = pair2;
        }

        for (int i = 0; i < M; i++) {
            System.out.println(pairs2[i].id);
        }
    }
}