# Task
 Given string `s`, which contains only letters from `a to z` in lowercase.

 A set of alphabet is given by `abcdefghijklmnopqrstuvwxyz`.
 
 2 sets of alphabets mean 2 or more alphabets.
 
 Your task is to find the missing letter(s). You may need to output them by the order a-z. It is possible that there is more than one missing letter from more than one set of alphabet.

 If the string contains all of the letters in the alphabet, return an empty string `""`

# Example

 For `s='abcdefghijklmnopqrstuvwxy'`

 The result should be `'z'`

 For `s='aabbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyy'`
 
 The result should be `'zz'`

 For `s='abbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxy'`
 
 The result should be `'ayzz'`

 For `s='codewars'`
 
 The result should be `'bfghijklmnpqtuvxyz'`

# Input/Output


 - `[input]` string `s`

  Given string(s) contains one or more set of alphabets in lowercase.


 - `[output]` a string

  Find the letters contained in each alphabet but not in the string(s). Output them by the order `a-z`. If missing alphabet is repeated, please repeat them like `"bbccdd"`, not `"bcdbcd"`

```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 collections import Counter\n\ndef missing_alphabets(s):\n    a, C = [], []\n    count = Counter(s)\n    \n    for i in range(1,max(count.values()) + 1):\n        a.append([k for k,v in list(count.items()) if v >= i ])\n    \n\n    A = "abcdefghijklmnopqrstuvwxyz"\n    B = [I for I in A if I not in s]\n    \n\n    for i in range(0 ,len(a)):\n        C.append([I for I in A if I not in a[i]])\n\n    return \'\'.join(sorted([j for i in C for j in i])) \n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'missing_alphabets'
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: 12418