Problem:
Score : 500 points

Problem Statement

You are given a string S of length N consisting of lowercase English letters.

Process Q queries of the following two types:

Type 1: change the i_q-th character of S to c_q. (Do nothing if the i_q-th character is already c_q.)

Type 2: answer the number of different characters occurring in the substring of S between the l_q-th and r_q-th characters (inclusive).

Constraints

N, Q, i_q, l_q, and r_q are integers.

S is a string consisting of lowercase English letters.

c_q is a lowercase English letter.

1 \leq N \leq 500000

1 \leq Q \leq 20000

|S| = N

1 \leq i_q \leq N

1 \leq l_q \leq r_q \leq N

There is at least one query of type 2 in each testcase.

Input

Input is given from Standard Input in the following format:

N
S
Q
Query_1
\vdots
Query_Q

Here, Query_i in the 4-th through (Q+3)-th lines is one of the following:

1 i_q c_q

2 l_q r_q

Output

For each query of type 2, print a line containing the answer.

Sample Input 1

7
abcdbbd
6
2 3 6
1 5 z
2 1 1
1 4 a
1 7 d
2 1 7

Sample Output 1

3
1
5

In the first query, cdbb contains three kinds of letters: b , c , and d, so we print 3.

In the second query, S is modified to abcdzbd.

In the third query, a contains one kind of letter: a, so we print 1.

In the fourth query, S is modified to abcazbd.

In the fifth query, S does not change and is still abcazbd.

In the sixth query, abcazbd contains five kinds of letters: a, b, c, d, and z, so we print 5.

Solution in Rust (1.42.0) (judge verdict: Accepted)

#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

pub trait Monoid {
    type T: Clone;
    fn id() -> Self::T;
    fn op(a: &Self::T, b: &Self::T) -> Self::T;
}
pub struct SegTree<M: Monoid> {
    n: usize,
    data: Vec<M::T>,
}
impl<M: Monoid> SegTree<M> {
    pub fn new(n_: usize) -> SegTree<M> {
        let mut n = 1 as usize;
        while (n < n_) {
            n *= 2;
        }
        SegTree {
            n: n,
            data: vec![M::id().clone(); (2 * n)],
        }
    }
    #[macro_use]
    pub fn update(&mut self, index: usize, v: M::T) {
        let mut k = index + self.n - 1;
        self.data[k] = v;
        while (k > 0) {
            k = (k - 1) / 2;
            self.data[k] = M::op(&self.data[2 * k + 1], &self.data[2 * k + 2]);
        }
    }
    pub fn query(&mut self, l: usize, r: usize) -> M::T {
        let mut l = l + self.n - 1;
        let mut r = r + self.n - 1;
        if (l == r) {
            return M::op(&M::id().clone(), &self.data[l]);
        }
        let mut ret = M::id().clone();
        while (l < r) {
            if (l % 2 == 0) {
                ret = M::op(&ret, &self.data[l]);
            }
            if (r % 2 == 0) {
                ret = M::op(&ret, &self.data[r - 1]);
            }
            l = l / 2;
            r = (r - 1) / 2;
        }
        return ret;
    }
}
struct OR;
impl Monoid for OR {
    type T = u64;
    fn id() -> Self::T {
        0
    }
    fn op(a: &Self::T, b: &Self::T) -> Self::T {
        *a | *b
    }
}

fn trs(s: char) -> u64 {
    1_u64 << (s as usize - 'a' as usize)
}

fn main() {
    input! {
       N: usize,
       S:Chars,
       Q:usize,
    }

    let mut st: SegTree<OR> = SegTree::new(N);
    for i in 0..N {
        st.update(i, trs(S[i]));
    }

    for _ in 0..Q {
        input! {
            t:usize,
        }
        if t == 1 {
            input! {
                index:Usize1,
                c:char,
            }
            st.update(index, trs(c));
        } else {
            input! {
                l:Usize1,
                r:Usize1,
            }
            let flag = st.query(l, r + 1);
            let mut sum = 0;
            for i in 0..63 {
                sum += flag >> i & 1;
            }
            echo!(sum);
        }
    }
}