### Longest Palindrome

Find the length of the longest substring in the given string `s` that is the same in reverse.        

As an example, if the input was “I like racecars that go fast”, the substring (`racecar`) length would be `7`. 

If the length of the input string is `0`, the return value must be `0`. 

### Example:
```
"a" -> 1 
"aab" -> 2  
"abcde" -> 1
"zzbaabcd" -> 4
"" -> 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 = '"""\n***************************************\n*   O(n) time complexity solution !   *\n***************************************\n"""\n\ndef longest_palindrome (s):\n\n    maxPal, tmpPal = 0, 1\n    count_dct = {}\n    inPal = False\n    \n    for i,l in enumerate(s):\n    \n        count_dct[l] = count_dct.get(l,0) + 1\n        \n        if not inPal and count_dct[l] >= 2:            # might encounter a palindrome, there...\n            if l == s[i-1]:                            # ... palindrome with double character in the middle\n                inPal = True\n                tmpPal = 2\n            \n            elif l == s[i-2]:                          # ... palindrome with one "peak" character in the middle\n                inPal = True\n                tmpPal = 3\n        \n        elif inPal and l == s[max(0, i-tmpPal-1)]:     # still in a palindrome...\n                tmpPal += 2\n            \n        else:                                          # goes out of this palindrome\n            inPal = False\n            tmpPal = 1\n        \n        maxPal = max(maxPal, tmpPal)\n    \n    return maxPal'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'longest_palindrome'
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: 5850