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 collections import defaultdict\nfrom bisect import bisect_left, bisect_right, insort_left, insort_right\nimport sys\ninput = sys.stdin.readline\n\n\ndef main():\n    N = int(input())\n    S = list(input())\n    q = int(input())\n    Q = [input() for _ in range(q)]\n\n    dd = defaultdict(list)  # 各アルファベットが出現するインデックスをddに登録\n    for i in range(ord('a'), ord('z') + 1):\n        dd[chr(i)] = []\n    for i, st in enumerate(S):\n        dd[st].append(i)\n\n    ans = []\n    for q in Q:\n        t, a, b = q.split()\n        a = int(a) - 1\n        if int(t) == 1:\n            if S[a] == b: continue\n            # 二分探索で該当するインデックスを取得\n            id = bisect_left(dd[S[a]], a)\n            dd[S[a]].pop(id)  # 取ってくる\n            insort_left(dd[b], a)  # 新規に挿入する\n            S[a] = b\n        else:\n            b = int(b) - 1\n            cnt = 0\n            for l in dd.values():\n                # liの中身が存在し，\n                # そのアルファベットの最後のインデックスが指定されている最初のindexよりも大きく．\n                # a以上の最初のindexがb以下の時は，そのアルファベットの存在は保証される\n                if l and a <= l[-1] and l[bisect_left(l, a)] <= b:\n                    cnt += 1\n            ans.append(cnt)\n    print(*ans, sep='\\n')\n\ndef __starting_point():\n    main()\n__starting_point()"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 15263