Find the closest prime number under a certain integer ```n``` that has the maximum possible amount of even digits.

For ```n = 1000```, the highest prime under ```1000``` is ```887```, having two even digits (8 twice)

Naming ```f()```, the function that gives that prime, the above case and others will be like the following below.
```
f(1000) ---> 887 (even digits: 8, 8)

f(1210) ---> 1201 (even digits: 2, 0)

f(10000) ---> 8887

f(500) ---> 487

f(487) ---> 467
``` 
Features of the random tests:
```
Number of tests = 28
1000 <= n <= 5000000
```

Enjoy it!!

```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 is_prime(n):\n    #base cases handling\n    if n == 2 or n == 3: return True #handles 2, 3\n    if n < 2 or n%2 == 0: return False #handles 1 and even numbers\n    if n < 9: return True #since 1, 2, 3, 4, 6 and 8 are handled, this leaves 5 and 7.\n    if n%3 == 0: return False #handles multiples of 3\n    r = int(n**0.5) #only check upto square root\n    f = 5 #start from 5\n    while f <= r:\n        #print ('\\t', f)\n        if n%f == 0: return False #essentially checks 6n - 1 for all n.\n        if n%(f+2) == 0: return False #essentially checks 6n + 1 for all n.\n        f +=6 #incrementing by 6.\n    return True\n\ndef max_even_digits_in_prime(n):\n    return (len(str(n)) - 1) or 1\n\ndef count_of_even_digits(n):\n    count = 0\n    for i in str(n):\n        count+= (int(i) % 2 == 0)\n    return count\n\ndef f(n):\n    best_case = (0, 0) #keeps track of highest best case number seen[1], and its count of even digits[0]\n    for x in range(n-1, 1, -1): #iterate in the reverse direction\n        #print(x)\n        if is_prime(x): #proceed for prime numbers\n            even_digits = count_of_even_digits(x)\n            max_even_digits = max_even_digits_in_prime(x)\n            if best_case[0] < even_digits: #update best number seen so far\n                best_case = (even_digits, x)\n            if max_even_digits == best_case[0]: #best case answer, your work is done. No need to look for more numbers.\n                print(best_case)\n                return (best_case[1])"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'f'
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: 6507