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,ele=0):\n        self.ide_ele = ele\n        self.num =2**(n-1).bit_length()\n        self.seg=[self.ide_ele]*2*self.num\n\n    def segfunc(self,x,y):\n        return x|y\n\n    def init(self,init_val):\n        for i in range(len(init_val)):\n            self.seg[i+self.num-1]=init_val[i]\n        for i in range(self.num-2,-1,-1) :\n            self.seg[i]=self.segfunc(self.seg[2*i+1],self.seg[2*i+2]) \n\n    def update(self,k,x):\n        k += self.num-1\n        if self.seg[k]==x:\n          return 0\n        self.seg[k] = x\n        while k:\n            k = (k-1)//2\n            self.seg[k] = self.segfunc(self.seg[k*2+1],self.seg[k*2+2])\n\n    def query(self,p,q):\n        if q<=p:\n            return self.ide_ele\n        p += self.num-1\n        q += self.num-2\n        res=self.ide_ele\n        while q-p>1:\n            if p&1 == 0:\n                res = self.segfunc(res,self.seg[p])\n            if q&1 == 1:\n                res = self.segfunc(res,self.seg[q])\n                q -= 1\n            p = p//2\n            q = (q-1)//2\n        if p == q:\n            res = self.segfunc(res,self.seg[p])\n        else:\n            res = self.segfunc(self.segfunc(res,self.seg[p]),self.seg[q])\n        return res\n      \nN,S,Q=int(input()),input(),int(input())\nd={'a': 1, 'b': 2, 'c': 4, 'd': 8, 'e': 16, 'f': 32, 'g': 64, 'h': 128, 'i': 256, 'j': 512, 'k': 1024, 'l': 2048, 'm': 4096, 'n': 8192, 'o': 16384, 'p': 32768, 'q': 65536, 'r': 131072, 's': 262144, 't': 524288, 'u': 1048576, 'v': 2097152, 'w': 4194304, 'x': 8388608, 'y': 16777216, 'z': 33554432}\n\ninitial=[d[c] for c in list(S)]\n\nST=SegmentTree(N)\nST.init(initial)\n\nfor _ in range(Q):\n    typ,a,b=input().split()\n    if typ=='1':\n        i,c=int(a),d[b]\n        ST.update(i-1,c)\n    else:\n        l,r=int(a)-1,int(b)\n        x=bin(ST.query(l,r))[2:]\n        print(sum(map(int,list(x))))"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16881