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 PHP7 (7.0.15) (judge verdict: Time Limit Exceeded)

<?php

    // 標準入力を配列化して取得する
    function get_input() {
        $input = [];
        while ($line = fgets(STDIN)) {
            $input[] = trim($line);
        }
        return $input;
    }

    // 末尾に改行をつけて出力
    function output($str) {
        echo $str . PHP_EOL;
    }

    $input = get_input();

    $s = $input[1];

    for ($i = 3; $i < count($input); $i++) {
        list($type, $a, $b) = explode(' ', $input[$i]);
        if ($type == 1) {
            $wk = str_split($s);
            if ($wk[$a - 1] != $b) {
                $wk[$a - 1] = $b;
            }
            $s = implode('', $wk);
        } elseif ($type == 2) {
            $result = [];
            $wk = str_split($s);
            for ($j = $a - 1; $j < $b; $j++) {
                @$result[$wk[$j]] = true;
            }
            output(count($result));
        }
    }