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 = "# https://atcoder.jp/contests/abc157/tasks/abc157_e\n# セグメント木\n# 各文字をビットに対応させる(セグ木を26本持っても良い)\nimport sys\nread = sys.stdin.readline\n\n\ndef read_a_int():\n    return int(read())\n\n\nclass SegmentTree:\n    def __init__(self, ls: list, segfunc, identity_element):\n        '''\n        セグ木 (下書き)\n        一次元のリストlsを受け取り初期化する。O(len(ls))\n        区間のルールはsegfuncによって定義される\n        identity elementは単位元。e.g., 最小値を求めたい→inf, 和→0, 積→1, gcd→0\n        [単位元](https://ja.wikipedia.org/wiki/%E5%8D%98%E4%BD%8D%E5%85%83)\n        '''\n        self.ide = identity_element\n        self.func = segfunc\n        n = len(ls)\n        self.num = 2 ** (n - 1).bit_length()  # n以上の最小の2のべき乗\n        self.tree = [self.ide] * (2 * self.num - 1)  # −1はぴったりに作るためだけど気にしないでいい\n        for i, l in enumerate(ls):  # 木の葉に代入\n            self.tree[i + self.num - 1] = l\n        for i in range(self.num - 2, -1, -1):  # 子を束ねて親を更新\n            self.tree[i] = segfunc(self.tree[2 * i + 1], self.tree[2 * i + 2])\n\n    def update(self, i, x):\n        '''\n        i番目の要素をxに変更する(木の中間ノードも更新する) O(logN)\n        '''\n        i += self.num - 1\n        self.tree[i] = x\n        while i:  # 木を更新\n            i = (i - 1) // 2\n            self.tree[i] = self.func(self.tree[i * 2 + 1],\n                                     self.tree[i * 2 + 2])\n\n    def query(self, l, r):\n        '''\n        区間[l,r)に対するクエリをO(logN)で処理する。例えばその区間の最小値、最大値、gcdなど\n        '''\n        if r <= l:\n            return ValueError('invalid index (l,rがありえないよ)')\n        l += self.num\n        r += self.num\n        res = self.ide\n        while l<r:  # 右から寄りながら結果を結合していくイメージ\n            if l & 1:\n                res = self.func(res, self.tree[l-1])\n                l+=1\n            if r & 1:\n                r -= 1\n                res = self.func(res, self.tree[r-1])\n            l >>=1\n            r >>=1\n        return res\n\n\ndef segfunc(x, y):\n    # 処理したい内容\n    return x | y\n\n\ndef moji_to_bit(a):\n    return 1 << (ord(a) - ord('a'))\n\n\ndef bit_to_sum(n):\n    return sum([(n >> i) & 1 for i in range(n.bit_length())])\n\n\nN = read_a_int()\nS = read()[:-1]\nS_bit = [moji_to_bit(s) for s in S]\n\n# build segment tree\nst = SegmentTree(S_bit, segfunc, 0)\n\nQ = read_a_int()\nfor q in range(Q):\n    com, a, b = read().split()\n    if int(com) == 1:\n        i, c = int(a) - 1, b\n        st.update(i, moji_to_bit(c))\n    else:\n        l, r = int(a) - 1, int(b)\n        print((bit_to_sum(st.query(l, r))))\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 17429