Lot of junior developer can be stuck when they need to change the access permission to a file or a directory in an Unix-like operating systems.

To do that they can use the `chmod` command and with some magic trick they can change the permissionof a file or a directory. For more information about the `chmod` command you can take a look at the [wikipedia page](https://en.wikipedia.org/wiki/Chmod).

`chmod` provides two types of syntax that can be used for changing permissions. An absolute form using octal to denote which permissions bits are set e.g: 766.
Your goal in this kata is to define the octal you need to use in order to set yout permission correctly.

Here is the list of the permission you can set with the octal representation of this one.

- User
  - read (4)
  - write (2)
  - execute (1)
- Group
  - read (4)
  - write (2)
  - execute (1)
- Other
  - read (4)
  - write (2)
  - execute (1)
  
The method take a hash in argument this one can have a maximum of 3 keys (`owner`,`group`,`other`). Each key will have a 3 chars string to represent the permission, for example the string `rw-` say that the user want the permission `read`, `write` without the `execute`.
If a key is missing set the permission to `---`

**Note**: `chmod` allow you to set some special flags too (`setuid`, `setgid`, `sticky bit`) but to keep some simplicity for this kata we will ignore this one.

```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 functools import reduce\nfrom operator import or_\n\nSHIFTS = {'user': 6, 'group': 3, 'other': 0}\n\ndef chmod_calculator(perm):\n    return format(reduce(or_, (\n        (('r' in p) << 2 | ('w' in p) << 1 | ('x' in p)) << SHIFTS[user]\n        for user, p in perm.items()\n    ), 0), '03o')"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'chmod_calculator'
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: 5734