If we alternate the vowels and consonants in the string `"have"`, we get the following list, arranged alphabetically:
`['ahev', 'aveh', 'ehav', 'evah', 'vahe', 'veha']`. These are the only possibilities in which vowels and consonants are alternated. The first element, `ahev`, is alphabetically lowest. 

Given a string:
* alternate the vowels and consonants and return the lexicographically lowest element in the list
* If any two or more vowels or consonants must follow each other, return `"failed"`
* if the number of vowels and consonants are equal, the first letter of the result must be a vowel.

Examples: 

```Haskell
solve("codewars") = "failed". However you alternate vowels and consonants, two consonants must follow each other
solve("oruder") = "edorur"
solve("orudere") = "ederoru". This is the only option that allows you to alternate vowels & consonants.
```

```if c:
In C, return an allocated string even if the response is "failed".
```

Vowels will be any of "aeiou". Input will be a lowercase string, no spaces. See test cases for more examples. 

Good luck!

If you like this Kata, please try: 

[Consonant value](https://www.codewars.com/kata/59c633e7dcc4053512000073)

[Alternate capitalization](https://www.codewars.com/kata/59cfc000aeb2844d16000075)

```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 solve(s):\n    vowels = 'aeiou'\n    s_vowels = sorted(c for c in s if c in vowels)\n    s_consonants = sorted(c for c in s if c not in vowels)\n\n    diff = len(s_vowels) - len(s_consonants)\n    if diff == -1:\n        out_string = s_consonants.pop(0)\n        for v, c in zip(s_vowels, s_consonants):\n            out_string += v + c\n    elif diff == 0:\n        out_string = ''\n        for v, c in zip(s_vowels, s_consonants):\n            out_string += v + c\n    elif diff == 1:\n        out_string = s_vowels.pop(0)\n        for c, v in zip(s_consonants, s_vowels):\n            out_string += c + v\n    else:\n        return 'failed'\n    \n    return out_string"
_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: 6108