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 Rust (1.42.0) (judge verdict: Time Limit Exceeded)

use proconio::marker::Usize1;
use proconio::{fastout, input};
use std::collections::HashSet;

#[fastout]
fn main() {
    input! {
        n: usize,
        q: usize,
        ball: [usize; n],
        query: [(Usize1, Usize1); q],
    }
    let mut ball_flag = vec![false; n];
    let mut flag_count = 0;
    let mut set = HashSet::new();
    for (i, b) in ball.iter().enumerate().rev() {
        if !set.contains(b) {
            ball_flag[i] = true;
            flag_count += 1;
        }
        set.insert(b);
    }
    let mut query: Vec<_> = query.into_iter().enumerate().collect();
    query.sort_by(|a, b| (b.1).1.cmp(&(a.1).1));
    let mut right = ball.len() - 1;
    let mut res = vec![0; q];
    for qenu in query {
        let q = qenu.1;
        while q.1 < right {
            if ball_flag[right] {
                flag_count -= 1;
                for i in (0..right).rev() {
                    if ball[i] == ball[right] {
                        ball_flag[i] = true;
                        flag_count += 1;
                        break;
                    }
                }
            }
            right -= 1;
        }
        let mut lf_count = 0;
        for i in 0..q.0 {
            if ball_flag[i] {
                lf_count += 1;
            }
        }
        res[qenu.0] = flag_count - lf_count;
    }
    for r in res {
        println!("{}", r);
    }
}