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    def __init__(self, n, segment_func, identity_element):\n        self.n = n\n        self.num = 1 << (self.n - 1).bit_length()\n        self.segment_func = segment_func\n        self.identity_element = identity_element\n        self.segment_tree = [self.identity_element] * (2 * self.num)\n\n    def initialize(self, val_arr):\n        for i in range(self.n):\n            self.segment_tree[self.num + i] = val_arr[i]\n        for i in range(self.num - 1, 0, -1):\n            self.segment_tree[i] = self.segment_func(self.segment_tree[2 * i], self.segment_tree[2 * i + 1])\n\n    def update(self, idx, val):\n        idx += self.num\n        self.segment_tree[idx] = val\n        while idx > 1:\n            self.segment_tree[idx >> 1] = self.segment_func(self.segment_tree[idx], self.segment_tree[idx ^ 1])\n            idx >>= 1\n\n    def query(self, left, right):\n        res = self.identity_element\n        left += self.num\n        right += self.num\n        while left < right:\n            if left & 1:\n                res = self.segment_func(res, self.segment_tree[left])\n                left += 1\n            if right & 1:\n                res = self.segment_func(res, self.segment_tree[right - 1])\n            left >>= 1\n            right >>= 1\n        return res\n\n    def bisect_left(self, left, right, target):\n        left += self.num\n        right += self.num\n        left_min = -1\n        right_min = -1\n        while left < right:\n            if left & 1:\n                if self.segment_tree[left] >= target and left_min == -1:\n                    left_min = left\n                left += 1\n            if right & 1:\n                if self.segment_tree[right - 1] >= target:\n                    right_min = right - 1\n            left >>= 1\n            right >>= 1\n        if left_min != -1 or right_min != -1:\n            res = left_min if left_min != -1 else right_min\n            while res < self.num:\n                if self.segment_tree[2 * res] >= target:\n                    res *= 2\n                else:\n                    res *= 2\n                    res += 1\n            return res - self.num\n        else:\n            return self.n\n\n    def get_val(self, idx):\n        return self.segment_tree[self.num + idx]\n\n\ndef conv_to_int(x):\n    return 1 << (ord(x) - ord('a'))\n\n\ndef main():\n    n = int(input())\n    s = [conv_to_int(t) for t in list(input())]\n    q = int(input())\n    st = SegmentTree(n, lambda x, y: x | y, 0)\n    st.initialize(s)\n    for _ in range(q):\n        query = input().split()\n        if query[0] == '1':\n            st.update(int(query[1]) - 1, conv_to_int(query[2]))\n        else:\n            res = st.query(int(query[1]) - 1, int(query[2]))\n            ans = 0\n            while res:\n                ans += res & 1\n                res >>= 1\n            print(ans)\n\n\ndef __starting_point():\n    main()\n\n__starting_point()"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 18091