# Task
We know that some numbers can be split into two primes. ie. `5 = 2 + 3, 10 = 3 + 7`. But some numbers are not. ie. `17, 27, 35`, etc.. 

Given a positive integer `n`. Determine whether it can be split into two primes. If yes, return the maximum product of two primes. If not, return `0` instead.

# Input/Output

`[input]` integer `n`

A positive integer. 

`0 ≤ n ≤ 100000`

`[output]` an integer

The possible maximum product of two primes. or return `0` if it's impossible split into two primes.

# Example

For `n = 1`, the output should be `0`.

`1` can not split into two primes

For `n = 4`, the output should be `4`.

`4` can split into two primes `2 and 2`. `2 x 2 = 4`

For `n = 20`, the output should be `91`.

`20` can split into two primes `7 and 13` or `3 and 17`. The maximum product is `7 x 13 = 91`

```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 = 'from bisect import bisect\n\n\ndef prime_product(n):\n    bisect_point = bisect(primes, n // 2)\n\n    # If n is odd then pair must be (2, n - 2) or nothing. This is because 2 is the\n    # only even prime and to get an odd number you must add even + odd.\n    if n % 2:\n        return 2 * (n - 2) if n - 2 in prime_set else 0\n\n    # Check half of prime list (starting from the middle). Return product of first pair found.\n    for prime in primes[:bisect_point][::-1]:\n        if n - prime in prime_set:\n            return prime * (n - prime)\n\n    return 0  # Return 0 if no valid pair found.\n\n\ndef get_primes(n):\n    """Sieve of Eratosthenes to calculate all primes less than or equal to n.\n\n    Return set of primes.\n    """\n    primes = [True] * (n + 1)\n\n    for num in range(2, int(n ** 0.5) + 1):\n        if primes[num]:\n            primes[num * 2::num] = [False] * len(primes[num * 2::num])\n\n    return [i for i, x in enumerate(primes) if x and i > 1]\n\n\n# Calculate all primes up to max but only calculate primes once. Then reference master prime list in all test cases.\nmax_input = 100000\nprimes = get_primes(max_input)\nprime_set = set(primes)'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'prime_product'
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: 5466