Problem:
Score : 600 points

Problem Statement

We have N colored balls arranged in a row from left to right; the color of the i-th ball from the left is c_i.

You are given Q queries. The i-th query is as follows: how many different colors do the l_i-th through r_i-th balls from the left have?

Constraints

1\leq N,Q \leq 5 \times 10^5

1\leq c_i \leq N

1\leq l_i \leq r_i \leq N

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N Q
c_1 c_2 \cdots c_N
l_1 r_1
l_2 r_2
:
l_Q r_Q

Output

Print Q lines. The i-th line should contain the response to the i-th query.

Sample Input 1

4 3
1 2 1 3
1 3
2 4
3 3

Sample Output 1

2
3
1

The 1-st, 2-nd, and 3-rd balls from the left have the colors 1, 2, and 1 - two different colors.

The 2-st, 3-rd, and 4-th balls from the left have the colors 2, 1, and 3 - three different colors.

The 3-rd ball from the left has the color 1 - just one color.

Sample Input 2

10 10
2 5 6 5 2 1 7 9 7 2
5 5
2 4
6 7
2 2
7 8
7 9
1 8
6 9
8 10
6 8

Sample Output 2

1
2
2
1
2
2
6
3
3
3

Solution in Java (OpenJDK 11.0.6) (judge verdict: Time Limit Exceeded)

// Part of OpenGenus
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {

    private static int getDistinctElements(int[] arr, int i, int j){
        Set<Integer> set = new HashSet<>();

        for(; i<=j; i++)
            set.add(arr[i]);

        return set.size();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String ff = scanner.nextLine();
        String[] bb =  ff.split(" ");
        int t = Integer.valueOf(bb[1]);

        String s = scanner.nextLine();
        String[] a =  s.split(" ");
        int[] arr = new int[a.length];
        for(int i = 0; i < arr.length;  i++)
            arr[i] = Integer.valueOf(a[i]);

        while(t-- != 0){
            String range = scanner.nextLine();
            String[] r = range.split(" ");
            System.out.println(getDistinctElements(arr, Integer.valueOf(r[0])-1, Integer.valueOf(r[1])-1));
        }
    }
}