In this Kata, you will be given an integer `n` and your task will be to return `the largest integer that is <= n and has the highest digit sum`.

For example:
```
solve(100) = 99. Digit Sum for 99 = 9 + 9 = 18. No other number <= 100 has a higher digit sum.
solve(10) = 9
solve(48) = 48. Note that 39 is also an option, but 48 is larger.
```

Input range is `0 < n < 1e11`

More examples in the test cases.

Good luck!

```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 typing import List, Union\ndef digit_sum(n: Union[List[int], int]) -> int:\n    """\n    Finds the digit sum of the digits in an integer or list of positional integers\n    """\n    if isinstance(n, list):\n        return sum(n)        \n    return sum(int(ch) for ch in str(n))\n\ndef to_int(arr: List[int]) -> int:\n    """\n    Converts an array of positional integers into a single integer\n    """\n    return int(\'\'.join(str(n) for n in arr))\n\ndef bump(arr, i):\n    """\n    Takes the digits of an array and increments the digit at index i and decrements the digit at \n    index i + 1.\n    E.g. bump([1, 2, 8, 4], 1) -> [1, 2+1, 8-1, 4] -> [1, 3, 7, 4]\n    """\n    return arr[:i] + [arr[i] + 1] + [arr[i + 1] - 1] + arr[i+2:]\n\ndef solve(n: int) -> int:\n    """\n    Find the largest number <= n with the maximum digit sum\n    """\n    s = str(n)\n    # Decrement the first digit and convert all others to 9 as a baseline\n    option = [int(s[0]) - 1] + [9] * (len(s) - 1)\n    if digit_sum(option) > digit_sum(n):\n        for i in range(len(option) - 1):\n            # Keep bumping digit i in option while still a single digit and the int value <= n\n            while True:\n                if option[i] == 9:\n                    break\n                b = bump(option, i)\n                if to_int(b) > n:\n                    break\n                option = b\n        return to_int(option)\n    return n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'solve'
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: 7168