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    非再帰\n    segment tree\n    \'\'\'\n\n    def __init__(self, n, func, init=float(\'inf\')):\n        \'\'\'\n        n->配列の長さ\n        func:func(a,b)->val,\u3000func=minだとRMQになる\n        木の高さhとすると,\n        n:h-1までのノード数。h段目のノードにアクセスするために使う。\n        data:ノード。\n        parent:k->child k*2+1とk*2+2\n        \'\'\'\n        self.n = 2**(n-1).bit_length()\n        self.init = init\n        self.data = [init]*(2*self.n)\n        self.func = func\n\n    def set(self, k, v):\n        \'\'\'\n        値の初期化\n        \'\'\'\n        self.data[k+self.n-1] = v\n\n    def build(self):\n        \'\'\'\n        setの後に一斉更新\n        \'\'\'\n        for k in reversed(list(range(self.n-1))):\n            self.data[k] = self.func(self.data[k*2+1], self.data[k*2+2])\n\n    def update(self, k, a):\n        \'\'\'\n        list[k]=aに更新する。\n        更新ぶんをrootまで更新\n        \'\'\'\n        k += self.n-1\n        self.data[k] = a\n\n        while k > 0:\n            k = (k-1)//2\n            self.data[k] = self.func(self.data[k*2+1], self.data[k*2+2])\n\n    def query(self, l, r):\n        \'\'\'\n        [l,r)のfuncを求める\n        \'\'\'\n        L = l+self.n\n        R = r+self.n\n        ret = self.init\n        while L < R:\n            if R & 1:\n                R -= 1\n                ret = self.func(ret, self.data[R-1])\n            if L & 1:\n                ret = self.func(ret, self.data[L-1])\n                L += 1\n            L >>= 1\n            R >>= 1\n        return ret\n\nN = int(input())\nS = input()\nQ = int(input())\nSeg = SegmentTree(N, lambda x, y: x | y, 0)\n\ndef a2n(a):\n    return ord(a) - ord(\'a\')\n\ndef createBit(a):\n    return 1 << a2n(a)\n\nfor i, s in enumerate(S):\n    Seg.set(i, createBit(s))\nSeg.build()\n\nfor _ in range(Q):\n    t, l, r = input().split()\n    if int(t) == 1:\n        Seg.update(int(l)-1, createBit(r))\n    else:\n        print((bin(Seg.query(int(l)-1, int(r))).count(\'1\')))\n\n# N = int(input())\n# S = input()\n# Q = int(input())\n# queries = [list(input().split()) for _ in range(Q)]\n\n\n# def a2n(a):\n#     return ord(a)-ord("a")\n\n\n# def createInp(a):\n#     return 1 << a2n(a)\n\n\n# Seg = SegmentTree(len(S), lambda x, y: x | y, init=0)\n# for i, s in enumerate(S):\n#     Seg.set(i, createInp(s))\n# Seg.build()\n\n# for q, l, r in queries:\n#     if q == "1":\n#         Seg.update(int(l)-1, createInp(r))\n#     else:\n#         print(bin(Seg.query(int(l)-1, int(r))).count(\'1\'))\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16907