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\ninput = sys.stdin.readline\n\nclass SegTree:\n    def __init__(self, size, f=lambda x,y: x|y, e=0):\n        self.size = 2**(size-1).bit_length()\n        self.e = e\n        self.tree = [e] * (self.size*2)\n        self.f = f\n    \n    def init_tree(self, l):\n        for i in range(len(l)):\n            self.tree[i+self.size] = l[i]\n        for i in range(self.size - 1, -1, -1):\n            self.tree[i] = self.f(self.tree[i*2], self.tree[i*2+1])\n    \n    def update(self, i, v):\n        i += self.size\n        self.tree[i] = v\n        while i > 0:\n            i >>= 1\n            self.tree[i] = self.f(self.tree[i*2], self.tree[i*2+1])\n    \n    def query(self, l, r):\n        l += self.size\n        r += self.size\n        lval = self.e\n        rval = self.e\n        while l < r:\n            if l & 1:\n                lval = self.f(lval, self.tree[l])\n                l += 1\n            if r & 1:\n                r -= 1\n                rval = self.f(rval, self.tree[r])\n            l >>= 1\n            r >>= 1\n        return self.f(lval, rval)\n\ndef a2i(c):\n    return 1<<(ord(c) - ord("a"))\n\ndef main():\n    N = int(input())\n    S = [a2i(s) for s in input().strip()]\n    Q = int(input())\n\n    tree = SegTree(N+5)\n    tree.init_tree(S)\n\n    for _ in range(Q):\n        t, x, y = input().split()\n        if t == "1":\n            x = int(x) - 1\n            y = 1<<(ord(y) - ord("a"))\n            tree.update(x, y)\n        else:\n            x = int(x) - 1\n            y = int(y)\n            tmp = tree.query(x, y)\n            ans = 0\n            while tmp > 0:\n                ans += tmp & 1\n                tmp >>= 1\n            print(ans)\n\ndef __starting_point():\n    main()\n__starting_point()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 17931