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  """Segmant Tree for query process.\n\n  Args:\n    a (List[int]): array.\n    identity (int): identity element with f.\n  """\n  def __init__(self, a, identity=0):\n    self.a = a\n    self.n = len(a)\n    self.identity = identity\n    self.depth = (self.n - 1).bit_length()\n    self.segment = (1 << self.depth) - 1\n    self.tree = [identity] * (self.segment * 2 + 1)\n    self.tree[self.segment : self.n + self.segment] = a\n    for i in range(self.segment - 1, -1, -1):\n      self.tree[i] = self.f(self.tree[2*i+1], self.tree[2*i+2])\n\n  def update(self, i: int, x: int):\n    i += self.segment\n    self.tree[i] = x\n    while i:\n      i = (i - 1) // 2\n      self.tree[i] = self.f(self.tree[2*i+1], self.tree[2*i+2])\n\n  def query(self, l: int, r: int) -> int:\n    """Query at [l, r]\n\n    Args:\n      l (int): left\n      r (int): right\n\n    Returns:\n      int: result\n    """\n    if l > r:\n      return self.identity\n    l += self.segment\n    r += self.segment\n    res = self.identity\n    while l <= r:\n      if not l & 1:\n        res = self.f(self.tree[l], res)\n      if r & 1:\n        res = self.f(res, self.tree[r])\n      l = l // 2\n      r = (r - 2) // 2\n    return res\n\n  def f(self, x: int, y: int) -> int:\n    return x | y\n\nn = int(input())\ns = input()\nq = int(input())\na = ord(\'a\')\nsegment_tree = SegmentTree([1 << (ord(c) - a) for c in s])\nfor _ in range(q):\n  query = input().split()\n  if query[0] == \'1\':\n    i = int(query[1]) - 1\n    c = query[2]\n    segment_tree.update(i, 1 << (ord(c) - a))\n  else:\n    l = int(query[1]) - 1\n    r = int(query[2]) - 1\n    bit = segment_tree.query(l, r)\n    print(format(bit, \'b\').count(\'1\'))'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16970