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: Runtime Error)

use proconio::marker::Usize1;
use proconio::{fastout, input};

#[fastout]
fn main() {
    input! {
        n: usize,
        q: usize,
        ball: [usize; n],
        query: [(Usize1, Usize1); q],
    }
    let mut dup_index = vec![-1isize; n];
    let mut ball_memo = vec![-1isize; n];
    for (i, &b) in ball.iter().enumerate() {
        if dup_index[b] >= 0 {
            ball_memo[dup_index[b] as usize] = i as isize;
        }
        dup_index[b] = i as isize
    }
    let mut query_enum: Vec<_> = query.into_iter().enumerate().collect();
    query_enum.sort_by(|a, b| (b.1).0.cmp(&(a.1).0));
    let mut right = ball.len() - 1;
    let mut dup_list: Vec<usize> = Vec::with_capacity(n);
    let mut res = vec![0; q];
    // println!("q: {:?}", query_enum);
    // println!("m: {:?}", ball_memo);
    for qenum in query_enum {
        let q = qenum.1;
        while q.0 <= right {
            if ball_memo[right] >= 0 {
                dup_list.push(ball_memo[right] as usize);
            }
            if right <= 0 {
                break;
            }
            right -= 1
        }
        let mut c = q.1 - q.0 + 1;
        // println!("c: {}, q: {:?}", c, q);
        // println!("d: {:?}", dup_list);
        for i in &dup_list {
            if *i <= q.1 {
                c -= 1;
            }
        }
        res[qenum.0] = c;
    }
    for r in res {
        println!("{}", r);
    }
}