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 = 'from operator import or_\n \nclass SegmentTree:\n    def __init__(self, size, op, e):\n        self._op = op\n        self._e = e\n        self._size = size\n        t = 1 << (size - 1).bit_length()\n        self._offset = t - 1\n        self._data = [e] * (t * 2 - 1)\n \n    def __getitem__(self, key):\n        return self._data[self._offset + key]\n \n    def __setitem__(self, key, value):\n        op = self._op\n        data = self._data\n        i = self._offset + key\n        data[i] = value\n        while i >= 1:\n            i = (i - 1) // 2\n            data[i] = op(data[i * 2 + 1], data[i * 2 + 2])\n \n    def build(self, iterable):\n        op = self._op\n        data = self._data\n        data[self._offset:self._offset + self._size] = iterable\n        for i in range(self._offset - 1, -1, -1):\n            data[i] = op(data[i * 2 + 1], data[i * 2 + 2])\n \n    def query(self, start, end):\n        op = self._op\n        res = self._e\n        l = self._offset + start\n        r = self._offset + end\n        while l < r:\n            if l & 1 == 0:\n                res = op(res, self._data[l])\n            if r & 1 == 0:\n                res = op(res, self._data[r - 1])\n            l = l // 2\n            r = (r-1) // 2\n        return res\n \ndef str2bit(c):\n  return 1 << (ord(c) - ord(\'a\'))\n \nN = int(input())\nS = input()\n \nst = SegmentTree(N, or_, 0)\nst.build(str2bit(x) for x in S)\n \nM = int(input())\nfor i in range(M):\n  q, a, b = input().split()\n  if q == "1":\n    st[int(a)-1] = str2bit(b)\n  elif q == "2":\n    print(bin(st.query(int(a)-1,int(b))).count("1"))'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16825