>When no more interesting kata can be resolved, I just choose to create the new kata, to solve their own, to enjoy the process  --myjinxin2015 said

# Description:
 Given a string `str` that contains some "(" or ")". Your task is to find the longest substring in `str`(all brackets in the substring are closed). The result is the length of the longest substring.

 For example:
 ```
 str = "()()("
 findLongest(str) === 4 
 "()()" is the longest substring
 ```
 
# Note:
 - All inputs are valid.
 - If no such substring found, return 0.
 - Please pay attention to the performance of code. ;-)
 - In the performance test(100000 brackets str x 100 testcases), the time consuming of each test case should be within 35ms. This means, your code should run as fast as a rocket ;-) 
 
# Some Examples
 ```
 findLongest("()") === 2
 findLongest("()(") === 2
 findLongest("()()") === 4
 findLongest("()()(") === 4
 findLongest("(()())") === 6
 findLongest("(()(())") === 6
 findLongest("())(()))") === 4
 findLongest("))((") === 0
 findLongest("") === 0
 ```

```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 = 'def find_longest(st):\n    stack=[-1]\n    longest=0\n    for index in range(0,len(st)):\n        if(st[index]=="("):\n            stack.append(index)\n        else:\n            stack.pop()\n            if stack:\n                longest=max(longest,index-stack[-1])\n            else:\n                stack.append(index)\n    print(longest)\n    return longest'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'find_longest'
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: 5786