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\n# import re\nimport math\nimport collections\n# import decimal\nimport bisect\nimport itertools\nimport fractions\n# import functools\nimport copy\n# import heapq\nimport decimal\n# import statistics\nimport queue\n\n# import numpy as np\n\nsys.setrecursionlimit(10000001)\nINF = 10 ** 16\nMOD = 10 ** 9 + 7\n# MOD = 998244353\n\nni = lambda: int(sys.stdin.readline())\nns = lambda: list(map(int, sys.stdin.readline().split()))\nna = lambda: list(map(int, sys.stdin.readline().split()))\n\n\n# ===CODE===\ndef main():\n    n = ni()\n    s = list(input())\n    q = ni()\n\n    alphabet_idx = {}\n    for i in range(26):\n        alphabet_idx[i] = []\n\n    for i, si in enumerate(s):\n        alphabet_idx[ord(si) - ord("a")].append(i)\n\n    for _ in range(q):\n        qi, a, b = input().split()\n        qi, a = int(qi), int(a)\n\n        if qi == 1:\n            a -= 1\n            if s[a] == b:\n                continue\n            del_char = ord(s[a]) - ord("a")\n            del_idx = bisect.bisect_left(alphabet_idx[del_char], a)\n            del alphabet_idx[del_char][del_idx]\n\n            insert_char = ord(b) - ord("a")\n            insert_idx = bisect.bisect_left(alphabet_idx[insert_char], a)\n            alphabet_idx[insert_char].insert(insert_idx, a)\n\n            s[a] = b\n\n        if qi == 2:\n            b = int(b)\n            a -= 1\n            b -= 1\n            ans = 0\n\n            for i in range(26):\n                a_idx = bisect.bisect_left(alphabet_idx[i], a)\n                if a_idx < len(alphabet_idx[i]):\n                    if alphabet_idx[i][a_idx] <= b:\n                        ans += 1\n\n            print(ans)\n\n\ndef __starting_point():\n    main()\n\n__starting_point()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 423218