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)

from collections import *
from itertools import *
from bisect import *
from heapq import *
import copy
import math


#N,K=map(int,input().split())
N=int(input())
S=input()
Q=int(input())
Query=[input.split() for i in range(Q)]

def segfunc(x,y):
    return (x|y)

def init(init_val):
    #set_val
    for i in range(n):
        seg[i+num-1]=init_val[i]
    #built
    for i in range(num-2,-1,-1) :
        seg[i]=seg[2*i+1]|seg[2*i+2]

def update(k,b):
    k += num-1
    if seg[k]=={b}:
        return ()
    seg[k] = {b}
    while k:
        k = (k-1)>>1
        seg[k] = seg[k*2+1]|seg[k*2+2]

def query(p,q):
    if q<=p:
        return ide_ele
    p += num-1
    q += num-2
    res=set()
    while q-p>1:
        if p&1 == 0:
            res = res|seg[p]
        if q&1 == 1:
            res = res|seg[q]
            q -= 1
        p = p>>1
        q = (q-1)>>1
    if p == q:
        res = res|seg[p]
    else:
        res = res|seg[p]|seg[q]
    return res

#num:n以上の最小の2のべき乗
n=N
num =2**(n-1).bit_length()
seg=[set()] * (2*num)

for i in range(N):
    seg[i+num-1]={ord(S[i])}
for k in range(num-2,-1,-1):
    seg[k] = seg[k*2+1]|seg[k*2+2]
for type, i, c in Query:
    if type=="1":
        update(int(i)-1,ord(c))
    else:
        print(len(query(int(i)-1,int(c))))
    #print(seg)