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 = 'import sys\ndef input(): return sys.stdin.readline().rstrip()\n\n# ライブラリ参照https://atcoder.jp/contests/practice2/submissions/16580070\nclass SegmentTree:\n\n    __slots__ = ["func", "e", "original_size", "n", "data"]\n\n    def __init__(self, length_or_list, func, e):\n        self.func = func\n        self.e = e\n        if isinstance(length_or_list, int):\n            self.original_size = length_or_list\n            self.n = 1 << ((length_or_list - 1).bit_length())\n            self.data = [self.e] * self.n\n        else:\n            self.original_size = len(length_or_list)\n            self.n = 1 << ((self.original_size - 1).bit_length())\n            self.data = [self.e] * self.n + length_or_list + \\\n                [self.e] * (self.n - self.original_size)\n            for i in range(self.n-1, 0, -1):\n                self.data[i] = self.func(self.data[2*i], self.data[2*i+1])\n\n    def replace(self, index, value):\n        index += self.n\n        self.data[index] = value\n        index //= 2\n        while index > 0:\n            self.data[index] = self.func(\n                self.data[2*index], self.data[2*index+1])\n            index //= 2\n\n    def folded(self, l, r):\n        left_folded = self.e\n        right_folded = self.e\n        l += self.n\n        r += self.n\n        while l < r:\n            if l % 2:\n                left_folded = self.func(left_folded, self.data[l])\n                l += 1\n            if r % 2:\n                r -= 1\n                right_folded = self.func(self.data[r], right_folded)\n            l //= 2\n            r //= 2\n        return self.func(left_folded, right_folded)\n\n    def all_folded(self):\n        return self.data[1]\n\n    def __getitem__(self, index):\n        return self.data[self.n + index]\n\n    def max_right(self, l, f):\n        # assert f(self.e)\n        if l >= self.original_size:\n            return self.original_size\n        l += self.n\n        left_folded = self.e\n        while True:\n            # l //= l & -l\n            while l % 2 == 0:\n                l //= 2\n            if not f(self.func(left_folded, self.data[l])):\n                while l < self.n:\n                    l *= 2\n                    if f(self.func(left_folded, self.data[l])):\n                        left_folded = self.func(left_folded, self.data[l])\n                        l += 1\n                return l - self.n\n            left_folded = self.func(left_folded, self.data[l])\n            l += 1\n            if l == l & -l:\n                break\n        return self.original_size\n\n    # 未verify\n    def min_left(self, r, f):\n        # assert f(self.e)\n        if r == 0:\n            return 0\n        r += self.n\n        right_folded = self.e\n        while True:\n            r //= r & -r\n            if not f(self.func(self.data[r], right_folded)):\n                while r < self.n:\n                    r = 2 * r + 1\n                    if f(self.func(self.data[r], right_folded)):\n                        right_folded = self.func(self.data[r], right_folded)\n                        r -= 1\n                return r + 1 - self.n\n            if r == r & -r:\n                break\n        return 0\n\n\ndef orr(x, y):\n    return x | y\n\n\ndef main():\n    N = int(input())\n    S = input()\n    S = list(map(lambda c: 2**(ord(c) - ord(\'a\')), list(S)))\n    Q = int(input())\n    seg = SegmentTree(S, orr, 0)\n    for _ in range(Q):\n        num, x, y = input().split()\n        if num == \'1\':\n            seg.replace(int(x)-1, 2**(ord(y) - ord(\'a\')))\n        else:\n            bits = seg.folded(int(x)-1, int(y))\n            print(sum(map(int, list(bin(bits))[2:])))\n\n\ndef __starting_point():\n    main()\n__starting_point()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 18823