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\ndef input(): return sys.stdin.readline().rstrip()\n\n\nclass SegTree:\n    X_unit = 0\n\n    def __init__(self, N, X_f=min):\n        self.N = N\n        self.X = [self.X_unit] * (N + N)\n        self.X_f = X_f\n\n    def build(self, seq):\n        for i, x in enumerate(seq, self.N):\n            self.X[i] = x\n        for i in range(self.N - 1, 0, -1):\n            self.X[i] = self.X_f(self.X[i << 1], self.X[i << 1 | 1])\n\n    def set_val(self, i, x):\n        i += self.N\n        self.X[i] = x\n        while i > 1:\n            i >>= 1\n            self.X[i] = self.X_f(self.X[i << 1], self.X[i << 1 | 1])\n\n    def fold(self, L, R):\n        L += self.N\n        R += self.N\n        vL = self.X_unit\n        vR = self.X_unit\n        while L < R:\n            if L & 1:\n                vL = self.X_f(vL, self.X[L])\n                L += 1\n            if R & 1:\n                R -= 1\n                vR = self.X_f(self.X[R], vR)\n            L >>= 1\n            R >>= 1\n        return self.X_f(vL, vR)\n\n\ndef orr(x, y):\n    return x | y\n\n\ndef main():\n    N = int(input())\n    S = input()\n    S = list(map(lambda c: 2**(ord(c) - ord('a')), list(S)))\n    Q = int(input())\n    seg = SegTree(N, orr)\n    seg.build(S)\n    for _ in range(Q):\n        num, x, y = input().split()\n        if num == '1':\n            seg.set_val(int(x)-1, 2**(ord(y) - ord('a')))\n        else:\n            bits=seg.fold(int(x)-1, int(y))\n            print(sum(map(int, list(bin(bits))[2:])))\n\n\ndef __starting_point():\n    main()\n__starting_point()"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 18253