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 math import log2, ceil\n\n\nclass SegTree:\n    #####単位元######\n    ide_ele = 0\n\n    def __init__(self, init_val):\n        n = len(init_val)\n        self.num = 2**ceil(log2(n))\n        self.seg = [self.ide_ele] * (2 * self.num - 1)\n\n        for i in range(n):\n            self.seg[i + self.num - 1] = init_val[i]\n\n        # built\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    #####segfunc######\n    def segfunc(self, x, y):\n        return x|y\n\n    def update(self, k, x):\n        k += self.num - 1\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, a, b, k, l, r):\n        if r <= a or b <= l:\n            return self.ide_ele\n        if a <= l and r <= b:\n            return self.seg[k]\n        else:\n            vl = self.query(a, b, k*2+1, l, (l+r)//2)\n            vr = self.query(a, b, k*2+2, (l+r)//2, r)\n            return self.segfunc(vl, vr)\n\n\nN = int(input())\nS = input()\nQ = int(input())\n\nli = [1 << (ord(s) - ord('a')) for s in S]\nseg_tree = SegTree(li)\nans = []\nfor _ in range(Q):\n    i, l, r = input().split()\n    i = int(i)\n    l = int(l)\n    if i == 1:\n        seg_tree.update(l-1, 1 << (ord(r) - ord('a')))\n    else:\n        r = int(r)\n        num = seg_tree.query(l-1, r, 0, 0, seg_tree.num)\n        ans.append(bin(num).count('1'))\n\nfor a in ans:\n    print(a)\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 16599