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\ninput = sys.stdin.readline\n\ndef segfunc(x,y):\n    return x | y\n\ndef init(init_val):\n    #set_val\n    for i in range(n):\n        seg[i+num-1]=init_val[i]\n    #built\n    for i in range(num-2,-1,-1) :\n        seg[i]=segfunc(seg[2*i+1],seg[2*i+2])\n\ndef update(k,x):\n    k += num-1\n    seg[k] = x\n    while k:\n        k = (k-1)//2\n        seg[k] = segfunc(seg[k*2+1],seg[k*2+2])\n\ndef query(p,q):\n    if q<=p:\n        return ide_ele\n    p += num-1\n    q += num-2\n    res=ide_ele\n    while q-p>1:\n        if p&1 == 0:\n            res = segfunc(res,seg[p])\n        if q&1 == 1:\n            res = segfunc(res,seg[q])\n            q -= 1\n        p = p//2\n        q = (q-1)//2\n    if p == q:\n        res = segfunc(res,seg[p])\n    else:\n        res = segfunc(segfunc(res,seg[p]),seg[q])\n    return res\n\n\nn = int(input())\ns = input()\nq = int(input())\n\nli = []\nfor i in range(n):\n    li.append(1 << ord(s[i]) - ord('a'))\n\n#####単位元######\nide_ele = 0\n\n#num:n以上の最小の2のべき乗\nnum =2**(n-1).bit_length()\nseg=[ide_ele]*2*num\ninit(li)\n\nfor _ in range(q):\n    q1 = list(input().split())\n    if q1[0] == '1':\n        update(int(q1[1]) - 1, 1 << ord(q1[2]) - ord('a'))\n    else:\n        l,r = int(q1[1]), int(q1[2])\n        print((bin(query(l-1,r)).count('1')))\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 14231