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
function qType1($s, $l, $r) {
    $s[--$l] = $r;
    return $s;
}

function qType2($s, $l, $r) {
    $uniq = [];
    for($i = intval($l) - 1; $i <= intval($r) - 1; $i++) {
        $uniq[$s[$i]] = true;
    }
    return count($uniq);
}
$n = intval(fgets(STDIN));
$s = fgets(STDIN);
$q = intval(fgets(STDIN));

for ($i = 0; $i < $q; $i++) {
    $q = explode(" ", fgets(STDIN));
    if ($q[0] == 1) {
        $s = qType1($s, $q[1], $q[2]);
    } else {
        echo qType2($s, $q[1], $q[2]) . "\n";
    }
}