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(object):\n    def __init__(self, sequence, function, identify):\n        N = len(sequence)\n        self.length = (1 << (N - 1)).bit_length()\n        self.function = function\n        self.data = [identify] * (self.length << 1)\n        self.identify = identify\n        # set values\n        for i in range(N):\n            self.data[i + self.length - 1] = sequence[i]\n        # build\n        for i in range(self.length - 2, -1, -1) :\n            self.data[i] = self.function(self.data[(i << 1) + 1], self.data[(i << 1) + 2])\n\n    def update(self, idx, x):\n        idx += self.length - 1\n        self.data[idx] = x\n        while idx:\n            idx = (idx - 1) >> 1\n            self.data[idx] = self.function(self.data[(idx << 1) + 1], self.data[(idx << 1) + 2])\n\n    def query(self, p, q):\n        if q <= p:\n            return self.identify\n        p += self.length - 1\n        q += self.length - 2\n        res = self.identify\n        while q - p > 1:\n            if not p & 1:\n                res = self.function(res, self.data[p])\n            if q & 1:\n                res = self.function(res, self.data[q])\n                q -= 1\n            p >>= 1\n            q = (q - 1) >> 1\n        return self.function(res, self.data[p]) if p == q else self.function(self.function(res, self.data[p]), self.data[q])\n\ndef popcount(x):\n    x = x - ((x >> 1) & 0x5555555555555555)\n    x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333)\n    x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f\n    x = x + (x >> 8)\n    x = x + (x >> 16)\n    x = x + (x >> 32)\n    return x & 0x0000007f\n\n\nN = int(input())\nS = input()\natoi = {chr(ord("a") + d): 1 << d for d in range(26)}\ndata = [atoi[c] for c in (S)]\nseg_tree = SegmentTree(data, lambda a, b: a | b, 0)\nQ = int(input())\nfor _ in range(Q):\n    q, a, b = input().split()\n    if q == "1":\n        idx = int(a) - 1\n        seg_tree.update(idx, atoi[b])\n    else:\n        print(popcount(seg_tree.query(int(a) - 1, int(b))))'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16607