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 = '# -*- coding: utf-8 -*-\n\n\'\'\'\n7\nabcdbbd\n6\n2 3 6\n1 5 z\n2 1 1\n1 4 a\n1 7 d\n2 1 7\n\'\'\'\n\n# from helper import elapsed_time\nfrom bisect import bisect_left, insort_left\n\n\nN = int(input())\ns = list(input())\nQ = int(input())\n\n# a-zまでの26文字に対して、s文字列の各文字に該当するindexを格納しておく\nd = {i: [] for i in range(26)}\nfor i, c in enumerate(s):\n    d[ord(c) - ord("a")].append(i)\n\n\n# @elapsed_time\ndef convert(d: dict, s: list, q1: int, q2: str):\n    if s[q1] == q2:\n        return d, s\n\n    didx_before = ord(s[q1]) - ord("a")\n    didx_after = ord(q2) - ord("a")\n\n    idx = bisect_left(d[didx_before], q1)\n    d[didx_before].pop(idx)\n    s[q1] = q2\n    insort_left(d[didx_after], q1)\n\n    return d, s\n\n\n# @elapsed_time\ndef calc(d: dict, q1: int, q2: int):\n    ans = 0\n    for i in range(26):\n        idx = bisect_left(d[i], q1)\n        if d[i] and q1 <= d[i][-1] and d[i][idx] < q2 + 1:\n            ans += 1\n\n    return ans\n\n\nfor _ in range(Q):\n    q, q1, q2 = input().split()\n    q = int(q)\n    if q == 1:\n        d, s = convert(d, s, int(q1) - 1, q2)\n    if q == 2:\n        print((calc(d, int(q1) - 1, int(q2) - 1)))\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 13393