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)

#![allow(
  non_snake_case,
  unused_variables,
  unused_assignments,
  unused_mut,
  unused_imports,
  dead_code
)]
//use proconio::fastout;
use proconio::input;
use proconio::marker::*;
use std::cmp::*;
use std::collections::*;
//use std::collections::VecDeque;

fn main() {
  input! {
     N:usize,Q:usize,
     c:[usize;N],
     lr:[(Usize1,Usize1);Q]
  }
  // 各色の最初の位置と最後の位置を記録する。
  //  let mut sta = HashMap::new();
  let mut end = HashMap::new();
  let mut ans = vec![0i64; N];
  let mut rli: Vec<(usize, usize, usize)> = lr
    .iter()
    .enumerate()
    .map(|(i, &(l, r))| (r, l, i))
    .collect();
  rli.sort();

  let mut cnt = 0;
  let mut j = 0;
  for i in 0..N {
    //    if sta.get(&c[i]) == None {
    //      sta.insert(c[i], i);
    //    }
    end.insert(c[i], i);
    
    for j in 0..Q {
      if rli[j].0 != i {
        continue;
      }
      let mut k = j;
      let mut rightmosts: Vec<usize> = end.values().map(|&v| v).collect();
      //println!("end:{:?}", end);
      rightmosts.sort();
      //println!("rightmosts:{:?}", rightmosts);
      let mut l = rli[k].1;
      let mut index = rli[k].2;
      let mut m = 0;
      let mut k = j;
      for m in 0..rightmosts.len() {
        while k < Q {
          if rli[k].0 != i {
            break;
          }
          if l <= rightmosts[m] {
            ans[index] = (rightmosts.len() - m) as i64;
            k += 1;
          } else {
            break;
          }
        }
      }
    }
  }
  for i in 0..Q {
    println!("{}", ans[i]);
  }
}