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 Kotlin (1.0.0) (judge verdict: Time Limit Exceeded)

fun main(args: Array<String>) {
    val N = nextInt()
    val S = next().map { it - 'a' }.toIntArray()
    val M = IntArray(N)
    for (n in 0 until N) { M[n] = M[n] or (1 shl S[n]) }
    val Q = nextInt()
    repeat(Q) {
        val q = listOfString()
        val k = q[0].toInt()
        if (k == 1) {
            val i = q[1].toInt() - 1
            val c = q[2][0] - 'a'
            M[i] = M[i] and (1 shl S[i]).inv()
            M[i] = M[i] or (1 shl c)
            S[i] = c
        } else {
            val l = q[1].toInt() - 1
            val r = q[2].toInt() - 1
            var chars = 0
            for (n in l .. r) {
                chars = chars or M[n]
            }
            var ans = 0
            while (chars > 0) {
                ans += chars % 2
                chars /= 2
            }
            println(ans)
        }
    }

}
fun next() = readLine()!!
fun nextInt() = next().toInt()
fun listOfString() = next().split(" ")