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-----
7
abcdbbd
6
2 3 6
1 5 z
2 1 1
1 4 a
1 7 d
2 1 7

-----Sample Output-----
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.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'class SegmentTree:\n    """\n    0-indexed\n    query : [L, R)\n    """\n    def __init__(self, size, initValue):\n        self.size = 1 << (size.bit_length())  # 完全二分木にする\n        self.data = [initValue] * (2 * self.size - 1)\n        self.initValue = initValue\n\n    def cmpFunc(self, left, right):\n        return left | right\n\n    def build(self, rawData):\n        self.data[self.size - 1: self.size - 1 + len(rawData)] = rawData\n        for i in range(self.size - 1)[:: -1]:\n            self.data[i] = self.cmpFunc(self.data[2 * i + 1], self.data[2 * i + 2])\n\n    def update(self, index, value):\n        index += self.size - 1\n        self.data[index] = value\n        while index >= 0:\n            index = (index - 1) // 2\n            self.data[index] = self.cmpFunc(self.data[2 * index + 1], self.data[2 * index + 2])\n\n    def query(self, left, right):\n        L = left + self.size\n        R = right + self.size\n        ret = self.initValue\n        while L < R:\n            if R & 1:\n                R -= 1\n                ret = self.cmpFunc(ret, self.data[R - 1])\n            if L & 1:\n                ret = self.cmpFunc(ret, self.data[L - 1])\n                L += 1\n            L >>= 1\n            R >>= 1\n        return ret\n\ndef cToI(s):\n    return ord(s) - ord(\'a\')\n\nN = int(input())\nS = list(map(cToI, input()))\n\nS = [1 << s for s in S]\ntree = SegmentTree(N, 0)\ntree.build(S)\n\nQ = int(input())\nans = []\nfor _ in range(Q):\n    q1, q2, q3 = input().split()\n\n    if q1 == \'1\':\n        tree.update(int(q2) - 1, 1 << cToI(q3))\n    else:\n        ans.append(tree.query(int(q2) - 1, int(q3)))\n\nfor a in ans:\n    cnt = 0\n    while a > 0:\n        cnt += a % 2\n        a //= 2\n    print(cnt)\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16962