Let's call any (contiguous) subarray B (of A) a mountain if the following properties hold:

B.length >= 3
There exists some 0 < i < B.length - 1 such that B[0] < B[1] < ... B[i-1] < B[i] > B[i+1] > ... > B[B.length - 1]

(Note that B could be any subarray of A, including the entire array A.)
Given an array A of integers, return the length of the longest mountain. 
Return 0 if there is no mountain.
Example 1:
Input: [2,1,4,7,3,2,5]
Output: 5
Explanation: The largest mountain is [1,4,7,3,2] which has length 5.

Example 2:
Input: [2,2,2]
Output: 0
Explanation: There is no mountain.

Note:

0 <= A.length <= 10000
0 <= A[i] <= 10000

Follow up:

Can you solve it using only one pass?
Can you solve it in O(1) space?

```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 longestMountain(self, A: List[int]) -> int:\n        up = down = ans = 0\n        for i in range(1, len(A)):\n            if A[i-1]==A[i]:\n                up = down = 0\n            elif A[i-1]<A[i]:\n                if down or up==0:\n                    up = 2\n                    down = 0\n                else:\n                    up += 1\n            else:\n                down += 1\n            if up and down:\n                ans = max(ans, up+down)\n        return ans\n    \n        \n        '''\n        up = down = ans = 0\n        for i in range(1, len(A)):\n            if A[i-1]>A[i] and up:\n                down += 1\n            if A[i-1]==A[i] or A[i-1]<A[i] and down or i==len(A)-1:\n                if up and down:\n                    ans = max(ans, up+down)\n                up = down = 0\n            if A[i-1]<A[i]:\n                up = 2 if not up else up+1\n\n        return ans\n        '''\n        \n        '''\n        l = ans = 0\n        phase = 0 #0:ascend, 1: descend\n        for r in range(1, len(A)):\n            if phase==0:\n                if A[r-1]==A[r]:\n                    l = r\n                elif A[r-1]>A[r]:\n                    if l+1<r:\n                        phase = 1\n                    else:\n                        l = r\n            if phase==1:\n                if A[r-1]<=A[r] or r==len(A)-1:\n                    ans = max(ans, r-l)\n                    if r==len(A)-1 and A[r-1]>A[r] and r-l==ans:\n                        ans += 1\n                    l = r if A[r-1]==A[r] else r-1\n                    phase = 0\n                          \n        return ans\n        ''' "
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'longestMountain'
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: 5530