Buggy python submission (verdict: Time Limit Exceeded):
# 本当はBITやセグメントツリーを用いた解法を使いたいところ...(理解不足)

import bisect
from collections import defaultdict

N = int(input())
# 書き換える時に文字列だと不便なのでリスト化しておく
S = list(input())
Q = int(input())

# setは順序を保証しない、setで管理するとクエリ2で（リスト化した後に）ソートする必要がある
# 最初からlistで管理して、クエリ1ではソート済になるように挿入する
dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)

    if a == 1:
        b = int(b) - 1
        # 書き換える必要がない場合
        if S[b] == c:
            continue
        else:
            # クエリ2が飛んできた時に毎回ソートしていては間に合わない
            # クエリ1の時点でソート済にしておく
            # 二分探索の際、同じ数字が既にあることはないので、leftでもrightでも良い
            dict[S[b]].remove(b)
            idx = bisect.bisect(dict[c], b)
            dict[c].insert(idx, b)
            # 文字列の書き換え
            S[b] = c

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        # 文字が何種類あるか
        char_cnt = 0
        for key, value in dict.items():
            # left,rightを指定する必要がある
            x1 = bisect.bisect_left(value, b)
            x2 = bisect.bisect_right(value, c)
            if x2 - x1 > 0:
                char_cnt += 1
        ans.append(char_cnt)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
from collections import defaultdict

N = int(input())
# 書き換える時に文字列だと不便なのでリスト化しておく
S = list(input())
Q = int(input())

dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)

    if a == 1:
        b = int(b) - 1
        if S[b] == c:
            continue
        else:
            dict[S[b]].remove(b)
            idx = bisect.bisect_left(dict[c], b)
            dict[c].insert(idx, b)
            S[b] = c

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            value.sort()
            x1 = bisect.bisect_left(value, b)
            x2 = bisect.bisect_right(value, c)
            if x2 - x1 > 0:
                char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Runtime Error):
import bisect
from collections import defaultdict
N = int(input())
S = input()
Q = int(input())

dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)

    if a == 1:
        b = int(b) - 1
        if S[b] == c:
            continue
        else:
            dict[S[b]].remove(b)
            idx = bisect_left(dict[c], b)
            dict[c].insert(idx, b)
            S[i] = c

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            if len(value)>0:
                x1 = bisect.bisect_left(value, b)
                x2 = bisect.bisect_right(value, c)
                if x2 - x1 > 0:
                    char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Runtime Error):
import bisect
from collections import defaultdict
N = int(input())
S = input()
Q = int(input())

dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)

    if a == 1:
        b = int(b) - 1
        if S[b] == c:
            continue
        else:
            dict[S[b]].remove(b)
            idx = bisect_left(dict[c], b)
            dict[c].insert(idx, b)
            S[i] = c

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            x1 = bisect.bisect_left(value, b)
            x2 = bisect.bisect_right(value, c)
            if x2 - x1 > 0:
                char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Time Limit Exceeded):
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

# {"a":[], "b":[], ..., "z":[]}
dict = {chr(ord('a') + i): [] for i in range(26)}

for i in range(N):
    dict[S[i]].append(i)

ans = []

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        # if now == x:
        #     continue
        dict[now].remove(i)
        next_i = bisect_left(dict[x], i)
        dict[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in dict.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        ans.append(tmp_cout)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Time Limit Exceeded):
# test!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Runtime Error):
import bisect
from collections import defaultdict
N = int(input())
S = input()
Q = int(input())

dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)
    if a == 1:
        b = int(b) - 1
        dict[S[b]].remove(b)
        idx = bisect.bisect_left(dict[c], b)
        dict[c].insert(idx, b)

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            if len(value) > 0:
                x1 = bisect.bisect_left(value, b)
                x2 = bisect.bisect_right(value, c)
                if x2 - x1 > 0:
                    char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Runtime Error):
import bisect
from collections import defaultdict
N = int(input())
S = input()
Q = int(input())

dict = defaultdict(list)
for i in range(N):
    dict[S[i]].append(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)
    if a == 1:
        b = int(b) - 1
        dict[S[b]].remove(b)
        idx = bisect.bisect_left(dict[c], b)
        dict[c].insert(idx, b)

    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            x1 = bisect.bisect_left(value, b)
            x2 = bisect.bisect_right(value, c)
            if x2 - x1 > 0:
                char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
from collections import defaultdict
N = int(input())
S = input()
Q = int(input())

dict = defaultdict(set)
for i in range(N):
    dict[S[i]].add(i)
# print(dict)

ans = []

for _ in range(Q):
    a, b, c = input().split()
    a = int(a)
    if a == 1:
        b = int(b) - 1
        for key in dict.keys():
            if b in dict[key]:
                dict[key].discard(b)
                dict[c].add(b)
                break
    elif a == 2:
        b = int(b) - 1
        c = int(c) - 1
        char_n = 0
        for key, value in dict.items():
            value = list(value)
            value.sort()
            x1 = bisect.bisect_left(value, b)
            x2 = bisect.bisect_right(value, c)
            if x2 - x1 > 0:
                char_n += 1
        ans.append(char_n)

for i in ans:
    print(i)


Fixed submission:
# test!!!!!!!!!!!

from bisect import bisect_left, bisect_right

N = int(input())

S = list(input())

Q = int(input())

memo = {chr(ord('a') + i): [] for i in range(26)}

for key,val in enumerate(S):
    memo[val].append(key)

for q in range(Q):
    query = list(input().split())
    if query[0] == '1':
        i, x = int(query[1])-1, query[2]
        now = S[i]
        if now == x:
            continue
        memo[now].remove(i)
        next_i = bisect_left(memo[x], i)
        memo[x].insert(next_i, i)
        S[i] = x
    else:
        start, end = int(query[1])-1, int(query[2])-1
        tmp_cout = 0
        for alf_array in memo.values():
            if len(alf_array) == 0:
                continue
            ss = bisect_left(alf_array, start)
            gg = bisect_right(alf_array, end)
            if gg- ss > 0:
                tmp_cout += 1
        print(tmp_cout)