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 = readLine()!!.toInt()
    val s = readLine()!!
    val map = mutableMapOf<Char, IntArray>()
    val tempCount = mutableMapOf<Char, Int>()
    for (c in 'a'..'z') {
        map[c] = IntArray(n) { 0 }
        tempCount[c] = 0
    }

    for (i in 0 until n) {
        tempCount[s[i]] = tempCount[s[i]]!! + 1
        for (c in 'a'..'z') {
            map[c]!![i] = tempCount[c]!!
        }
    }

    val q = readLine()!!.toInt()
    val qList = mutableListOf<Pair<Int, Char>>()
    for (x in 1..q) {
        val (type, t1, t2) = readLine()!!.split(' ')
        if (type == "1") {
            val i = t1.toInt() - 1
            val nexC = t2.toCharArray()[0]
            qList.add(Pair(i, nexC))

        } else {
            val l = t1.toInt() - 1
            val r = t2.toInt() - 1
            val countMap = mutableMapOf<Char, Int>()
            for (c in 'a'..'z') {
                countMap[c] = map[c]!![r] - if (l == 0) 0 else map[c]!![l - 1]
            }
            val tempS = s.toCharArray()
            for (ql in qList) {
                val (i, c) = ql
                if (i in l..r) {
                    val curC = tempS[i]
                    countMap[curC] = countMap[curC]!! - 1
                    countMap[c] = countMap[c]!! + 1
                    tempS[i] = c
                }
            }
            val count = countMap.count { it.value > 0 }
            println(count)
        }
    }
}