Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S, n):
        self.size = n
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


n = int(input())
S = list(input())
S = [s for s in S]
segtree = SegmentTree(S, 19)
for _ in range(int(input())):
    t, i, c = input().split()
    if t == '1':
        segtree.update(int(i)-1, c)
    if t == '2':
        print(segtree.query(int(i)-1, int(c)))


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    # リストSの部分リストからなる集合を葉とするセグメント木
    def __init__(self, S, n):
        self.size = n
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        # 配列のi番目をcに更新する
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    n = int(input())
    S = list(input())
    S = [ord(s) for s in S]
    segtree = SegmentTree(S, 19)
    for _ in range(int(input())):
        t, i, c = input().split()
        if t == '1':
            segtree.update(int(i)-1, ord(c))
        if t == '2':
            print(segtree.query(int(i)-1, int(c)))


main()


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    # リストSの部分リストからなる集合を葉とするセグメント木
    def __init__(self, S, n):
        self.size = n
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        # 配列のi番目をcに更新する
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


n = int(input())
S = list(input())
S = [ord(s) for s in S]
segtree = SegmentTree(S, 19)
for _ in range(int(input())):
    t, i, c = input().split()
    if t == '1':
        segtree.update(int(i)-1, ord(c))
    if t == '2':
        print(segtree.query(int(i)-1, int(c)))


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    # リストSの部分リストからなる集合を葉とするセグメント木
    def __init__(self, S, n):
        self.size = n
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        # 配列のi番目をcに更新する
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


n = int(input())
S = list(input())
S = [ord(s) for s in S]
segtree = SegmentTree(S, 19)
for _ in range(int(input())):
    t, i, c = input().split()
    if t == '1':
        segtree.update(int(i)-1, ord(c))
    if t == '2':
        print(segtree.query(int(i)-1, int(c)))


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


N = int(input())
S = [ord(_) - 97 for _ in list(input())]
Q = int(input())
tree = SegmentTree(S)
for q in range(Q):
    t, i, c = input().split()
    if t == '1':
    i = int(i) - 1
    tree.update(i, ord(c) - 97)
    else:
        l, r = int(i) - 1, int(c)
        print(tree.query(l, r))

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = list(input())
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, c)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        # tmp = len(S)
        # cnt = 0
        # while tmp // 2 > 0:
        #     tmp //= 2
        #     cnt += 1
        self.size = 19
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = list(input())
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, c)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        # tmp = len(S)
        # cnt = 0
        # while tmp // 2 > 0:
        #     tmp //= 2
        #     cnt += 1
        self.size = 19
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = list(input())
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, c)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        # tmp = len(S)
        # cnt = 0
        # while tmp // 2 > 0:
        #     tmp //= 2
        #     cnt += 1
        self.size = 19
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = list(input())
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, c)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        # tmp = len(S)
        # cnt = 0
        # while tmp // 2 > 0:
        #     tmp //= 2
        #     cnt += 1
        self.size = 19
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


N = int(input())
S = list(input())
Q = int(input())
tree = SegmentTree(S)
for q in range(Q):
    t, i, c = input().split()
    if t == '1':
        i = int(i) - 1
        tree.update(i, c)
    else:
        l, r = int(i) - 1, int(c)
        print(tree.query(l, r))
# S = ['a', 'b', 'c', 'd', 'b', 'b', 'd']
# tree = SegmentTree(S)
# print(tree.query(2, 6))


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        # tmp = len(S)
        # cnt = 0
        # while tmp // 2 > 0:
        #     tmp //= 2
        #     cnt += 1
        self.size = 20
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


N = int(input())
S = list(input())
Q = int(input())
tree = SegmentTree(S)
for q in range(Q):
    t, i, c = input().split()
    if t == '1':
        i = int(i) - 1
        tree.update(i, c)
    else:
        l, r = int(i) - 1, int(c)
        print(tree.query(l, r))
# S = ['a', 'b', 'c', 'd', 'b', 'b', 'd']
# tree = SegmentTree(S)
# print(tree.query(2, 6))


Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        tmp = len(S)
        cnt = 0
        while tmp // 2 > 0:
            tmp //= 2
            cnt += 1
        self.size = cnt + 1
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


N = int(input())
S = list(input())
Q = int(input())
tree = SegmentTree(S)
for q in range(Q):
    t, i, c = input().split()
    if t == '1':
        i = int(i) - 1
        tree.update(i, c)
    else:
        l, r = int(i) - 1, int(c)
        print(tree.query(l, r))

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
class SegmentTree():
    def __init__(self, S):
        # S:英小文字からなる配列
        tmp = len(S)
        cnt = 0
        while tmp // 2 > 0:
            tmp //= 2
            cnt += 1
        self.size = cnt + 1
        # sizeはSの長さ<=2**nをみたす最小のn
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


N = int(input())
S = list(input())
Q = int(input())
tree = SegmentTree(S)
for q in range(Q):
    t, i, c = input().split()
    if t == '1':
        i = int(i) - 1
        tree.update(i, c)
    else:
        l, r = int(i) - 1, int(c)
        print(tree.query(l, r))

Fixed submission:
import sys
input = sys.stdin.readline


class SegmentTree():
    def __init__(self, S):
        self.size = 19
        self.array = [set()] * (2**(self.size + 1) - 1)
        for i, c in enumerate(S):
            self.array[i + 2**self.size - 1] = {c}
        for i in range(2**self.size - 1)[::-1]:
            self.array[i] = self.array[2 * i + 1] | self.array[2 * i + 2]

    def subquery(self, l, r, k, i, j):
        # 区間[i,j)の中で区間[l,r)の文字列の集合を返す
        if j <= l or r <= i:
            return set()
        elif l <= i and j <= r:
            return self.array[k]
        else:
            l_set = self.subquery(l, r, 2 * k + 1, i, (i + j) // 2)
            r_set = self.subquery(l, r, 2 * k + 2, (i + j) // 2, j)
            return l_set | r_set

    def query(self, l, r):
        # [l,r)に含まれる文字の種類数
        return len(self.subquery(l, r, 0, 0, 2**self.size))

    def update(self, i, c):
        tmp = i + 2**self.size - 1
        self.array[tmp] = {c}
        while tmp > 0:
            tmp = (tmp - 1) // 2
            self.array[tmp] = self.array[2 * tmp + 1] | self.array[2 * tmp + 2]


def main():
    N = int(input())
    S = [ord(_) - 97 for _ in list(input())]
    Q = int(input())
    tree = SegmentTree(S)
    for q in range(Q):
        t, i, c = input().split()
        if t == '1':
            i = int(i) - 1
            tree.update(i, ord(c) - 97)
        else:
            l, r = int(i) - 1, int(c)
            print(tree.query(l, r))


if __name__ == '__main__':
    main()