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 = 'def segfunc(x, y):\n    return (x | y)\n\n\nide_ele = 0\n\n\nclass SegTree:\n    """\n    init(init_val, ide_ele): 配列init_valで初期化 O(N)\n    update(k, x): k番目の値をxに更新 O(logN)\n    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)\n    """\n\n    def __init__(self, init_val, segfunc, ide_ele):\n        """\n        init_val: 配列の初期値\n        segfunc: 区間にしたい操作\n        ide_ele: 単位元\n        n: 要素数\n        num: n以上の最小の2のべき乗\n        tree: セグメント木(1-index)\n        """\n        n = len(init_val)\n        self.segfunc = segfunc\n        self.ide_ele = ide_ele\n        self.num = 1 << (n - 1).bit_length()\n        self.tree = [ide_ele] * 2 * self.num\n        # 配列の値を葉にセット\n        for i in range(n):\n            self.tree[self.num + i] = init_val[i]\n        # 構築していく\n        for i in range(self.num - 1, 0, -1):\n            self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])\n\n    def update(self, k, x):\n        """\n        k番目の値をxに更新\n        k: index(0-index)\n        x: update value\n        """\n        k += self.num\n        self.tree[k] = x\n        while k > 1:\n            self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])\n            k >>= 1\n\n    def query(self, l, r):\n        """\n        [l, r)のsegfuncしたものを得る\n        l: index(0-index)\n        r: index(0-index)\n        """\n        res = self.ide_ele\n\n        l += self.num\n        r += self.num\n        while l < r:\n            if l & 1:\n                res = self.segfunc(res, self.tree[l])\n                l += 1\n            if r & 1:\n                res = self.segfunc(res, self.tree[r - 1])\n            l >>= 1\n            r >>= 1\n        return res\n\n\nn = int(input())\ns = input()\nq = int(input())\n\nls = []\n\nfor ch in s:\n    ls.append(1 << (ord(ch) - 97))\n\nseg = SegTree(ls, segfunc, ide_ele)\n\nfor i in range(q):\n    que = input().split()\n    if que[0] == \'1\':\n        iq = int(que[1])\n        cq = que[2]\n        seg.update(iq-1, 1 << (ord(cq) - 97))\n    else:\n        lq = int(que[1])\n        rq = int(que[2])\n        ret = seg.query(lq-1, rq)\n        print((str(bin(ret)).count(\'1\')))\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 17007