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: Wrong Answer)

#![allow(non_snake_case, unused_mut)]
//use petgraph::unionfind::UnionFind;
use proconio::marker::Usize1;
use proconio::{fastout, input, marker::*};
//use std::collections::HashMap;
use std::collections::HashSet;

#[fastout()]
fn main() {
    input! {
        N:usize, mut S:Chars, Q:usize,
    }
    let mut lsets = vec![HashSet::new(); N + 1];
    for i in 0..N {
        lsets[i + 1] = lsets[i].clone();
        lsets[i + 1].insert(S[i]);
    }
    let mut rsets = vec![HashSet::new(); N + 1];
    for i in (0..N).rev() {
        rsets[i] = rsets[i + 1].clone();
        rsets[i].insert(S[i]);
    }
    for _ in 0..Q {
        //println!("L{:?}", lsets);
        //println!("R{:?}", rsets);
        input! {query:i32}
        if query == 1 {
            input! {iq:Usize1,cq:char}
            if S[iq] == cq {
                continue;
            };
            let sq = S[iq];
            if !lsets[iq].contains(&sq) {
                for j in iq..N {
                    if S[j] != sq {
                        lsets[j + 1].remove(&sq);
                    } else {
                        break;
                    }
                }
            }
            if !lsets[iq].contains(&cq) {
                for j in iq..N {
                    if S[j] != cq {
                        lsets[j + 1].insert(cq);
                    } else {
                        break;
                    }
                }
            }
            if !rsets[iq + 1].contains(&sq) {
                for j in (0..iq).rev() {
                    if S[j] != sq {
                        rsets[j].remove(&sq);
                    } else {
                        break;
                    }
                }
            }
            if !rsets[iq + 1].contains(&cq) {
                for j in (0..iq).rev() {
                    if S[j] != cq {
                        rsets[j].insert(cq);
                    } else {
                        break;
                    }
                }
            }
            S[iq] = cq;
        } else {
            // queary 2の場合
            input! {lq:Usize1, rq:Usize1}
            //println!("L={:?},R{:?}", lsets[rq + 1], rsets[lq]);
            let ans = lsets[rq + 1]
                .intersection(&rsets[lq])
                .collect::<HashSet<_>>()
                .len();
            println!("{}", ans);
        }
    }
}