Given a string s, return the maximum number of ocurrences of any substring under the following rules:

The number of unique characters in the substring must be less than or equal to maxLetters.
The substring size must be between minSize and maxSize inclusive.

 
Example 1:
Input: s = "aababcaab", maxLetters = 2, minSize = 3, maxSize = 4
Output: 2
Explanation: Substring "aab" has 2 ocurrences in the original string.
It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize).

Example 2:
Input: s = "aaaa", maxLetters = 1, minSize = 3, maxSize = 3
Output: 2
Explanation: Substring "aaa" occur 2 times in the string. It can overlap.

Example 3:
Input: s = "aabcabcab", maxLetters = 2, minSize = 2, maxSize = 3
Output: 3

Example 4:
Input: s = "abcde", maxLetters = 2, minSize = 3, maxSize = 3
Output: 0

 
Constraints:

1 <= s.length <= 10^5
1 <= maxLetters <= 26
1 <= minSize <= maxSize <= min(26, s.length)
s only contains lowercase English letters.

```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

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = "class Solution:\n    def maxFreq(self, s: str, maxLetters: int, minSize: int, maxSize: int) -> int:\n        from collections import defaultdict\n        letters = defaultdict(int)\n        res = 0\n        if len(s) < minSize:\n            return 0\n        i = 0\n        j = 0\n        unique = 0\n        counter = defaultdict(int)\n        while i < len(s):\n            if letters[s[i]] == 0:\n                unique += 1\n            letters[s[i]] += 1\n            \n            while j < i and unique > maxLetters:\n                letters[s[j]] -= 1\n                if letters[s[j]] == 0:\n                    unique -= 1\n                j += 1\n            j_tmp = j\n            unique_tmp = unique\n            letters_tmp = letters.copy()\n            while unique_tmp <= maxLetters and (minSize <= (i - j_tmp + 1)):\n                if (i - j_tmp + 1) > maxSize:\n                    j_tmp+=1\n                    continue\n                counter[s[j_tmp:i+1]] += 1\n                #print(f'{s[j_tmp:i+1]} {counter} {i} {j_tmp}')\n                letters_tmp[s[j_tmp]] -= 1\n                if letters_tmp[s[j_tmp]] == 0:\n                    unique_tmp -= 1\n                j_tmp += 1\n                #print(f'i {i} j {j} unique {unique} {s[j:i+1]} letters {letters},res {res}, len {i-j+1}, {counter}')\n            i += 1\n        if len(counter.values()) == 0:\n            return 0\n        \n        return max(counter.values())"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'maxFreq'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 8622