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 {

    long INF = Long.MAX_VALUE;

    public static void main(String[] args) {
        new Main().solve();
    }

    void solve() {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();
        int[] pc = new int[N + 1];
        long[] P = new long[M];
        long[][] Y = new long[M][3];
        Arrays.fill(pc, 0);
        for (int i = 0; i < M; i++) {
            P[i] = sc.nextLong();
            Y[i][0] = sc.nextLong();
            Y[i][1] = i;
            Y[i][2] = P[i];
        }
        Arrays.sort(Y, (a, b) -> Long.compare(a[0], b[0]));
        for (int i = 0; i < M; i++) {
            pc[(int) Y[i][2]]++;
            Y[i][0] = pc[(int) Y[i][2]];
        }
        Arrays.sort(Y, (a, b) -> Long.compare(a[1], b[1]));
        for (int i = 0; i < M; i++) {
            if (String.valueOf(P[i]).length() == 2) {
                System.out.print("0000");
            } else if (String.valueOf(P[i]).length() == 3) {
                System.out.print("000");
            } else if (String.valueOf(P[i]).length() == 4) {
                System.out.print("00");
            } else if (String.valueOf(P[i]).length() == 5) {
                System.out.print("0");
            } else if (String.valueOf(P[i]).length() == 1) {
                System.out.print("00000");
            }
            System.out.println(P[i] * 1000000 + Y[i][0]);
        }
    }
}