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: Wrong Answer)

import java.util.*;

public class Main{
	public static void main(String args[]){
     	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int q = sc.nextInt();
        int ar[] = new int[n+1];
        HashSet<Integer> set = new HashSet<>();
        for(int i =0;i<n;i++){
         	set.add(sc.nextInt());
           ar[i+1] = set.size();
        }
      for(int i =0;i<q;i++){
      	 int a = sc.nextInt();
        int b = sc.nextInt();
        if(a==b)
          System.out.println(1);
        else{
          System.out.println(ar[b]-ar[a-1]);
        }
           
        }
    }
}