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 JavaScript (node.js v5.12) (judge verdict: Time Limit Exceeded)

"use strict";
function main(input) {
  let n = parseInt(input[0]);
  let s = input[1];
 
  let q_l = parseInt(input[2]);
  let q = [];
 
  for(let j=0;j<q_l;j++){
    let kari = input[j+3].trim().split(" ")
    q[j] = parseInt(kari[0]);
    if(q[j]===1){
      let i = parseInt(kari[1]);
      let c = kari[2];
      let str1 = s.slice(0, i-1);
      let str2 = s.slice(i);
 
      s = str1 + c + str2;
    }else{
      let l = parseInt(kari[1]);
      let r = parseInt(kari[2]);
      let str = s.slice(l-1, r);
 
      //カウント
      let list = {};
      let counter = 0;
 
      for(let i=0;i<str.length;i++){
        if(list[str[i]]===undefined){
          counter++;
          list[str[i]] = true;
        }
      }
      console.log(counter);
    }
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"));