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 SegTree:\n    def __init__(self, N, S):\n        self.N = 2 ** ((N-1).bit_length())\n        self.tree = [0 for i in range(self.N * 2 - 1)]\n        for i in range(len(S)):\n            self.tree[self.N - 1 + i] = 1 << (ord(S[i]) - ord("a"))\n\n        for i in range(self.N - 2, -1, -1):\n            self.tree[i] = self.tree[i*2 + 1] | self.tree[i*2 + 2]\n\n    def update(self, index, char):\n        i = self.N - 1 + index\n        # アルファベットがある = bitが立っている\n        self.tree[i] = 1 << (ord(char) - ord("a"))\n        while i > 0:\n            i = (i-1) // 2\n            self.tree[i] = self.tree[i*2 + 1] | self.tree[i*2 + 2]\n\n    def get(self, a, b):\n        return self.query(a, b, 0, 0, self.N)\n\n    # k : ノードの番号\n    # l : ノードkの受け持つ区間\n    # r : ノードkの受け持つ区間\n    def query(self, a, b, k, l, r):\n        if r <= a or b <= l: # 区間外\n            return 0\n        elif a <= l and r <= b: # 受け持ち区間は完全に含まれている\n            return self.tree[k]\n        else: # 一部含まれてる\n            left = self.query(a, b, 2 * k + 1, l, (l+r)//2)\n            right = self.query(a, b, 2 * k + 2, (l+r)//2, r)\n            return left | right\n\ndef solve():\n    N = int(input())\n    S = list(input().strip())\n    tree = SegTree(N, S)\n\n    Q = int(input())\n    for _ in range(Q):\n        t_q, in_1, in_2 = input().split()\n        if t_q == "1":\n            i_q = int(in_1)\n            c_q = in_2\n            tree.update(i_q-1, c_q)\n        else:\n            l_q = int(in_1)\n            r_q = int(in_2)\n            print(bin(tree.get(l_q-1, r_q)).count("1"))\n\nsolve()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 17051