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 PyPy3 (2.4.0) (judge verdict: Runtime Error)

import sys
def input():
    sys.stdin.buffer.readline()[:-1]
n = int(input())
ss = list(input())
q = int(input())
s = []
for i in range(len(ss)):
    a = ord(ss[i])-97
    s.append(a)
#print(s) #test
h = 0
nn = n
while nn:
    nn //= 2
    h += 1

seg = [[0 for _ in range(26)] for _ in range((2**(h+1))-1)]
for i in range(2**h-1, n-1+2**h):
    nl = [i] #所属するsegの番号リスト
    y = i
    for j in range(h):
        y = (y-1)//2
        nl.append(y) #nl完成
    for k in nl:
        seg[k][s[i-2**h+1]] += 1

for _ in range(q):
    bs, cs, ds = input().split()
    b = int(bs)
    c = int(cs)
    if b == 1:
        #print("クエリ1処理開始") #test
        f = ord(ds)-97
        x = c + 2**h - 2
        cl = [x]
        for j in range(h):
            x = (x-1)//2
            cl.append(x)
        #print(cl) #test
        #print(c) #test
        #print(s[c-1]) #test
        for k in cl:
            seg[k][s[c-1]] -= 1
            seg[k][f] += 1
        #print(seg) #test
    else:
        #print("クエリ2処理開始") #test
        d = int(ds)
        C = 2**h + c - 1
        D = 2**h + d
        LI = [] #敷居リスト
        t = C
        u = 1
        jud = False
        while True:
            if t * u == D:
                break
            elif t%2 != 0:
                if (t+1) * u <= D:
                    LI.append(t)
                    t += 1
                else:
                    t *= 2
                    u //= 2
            else:
                if (t+2) * u <= D:
                    t //= 2
                    u *= 2
                elif (t+1) * u <= D:
                    LI.append(t)
                    t += 1
                else:
                    t *= 2
                    u //= 2
        #print(LI)
        sumlist = [0 for _ in range(26)] #範囲内の個数
        for sh in LI:
            sh -= 1
            for j in range(26):
                sumlist[j] += seg[sh][j]
        #print(sumlist)
        ans = 0
        for numbers in sumlist:
            if numbers != 0:
                ans += 1
        print(ans)