I'm afraid you're in a rather unfortunate situation. You've injured your leg, and are unable to walk, and a number of zombies are shuffling towards you, intent on eating your brains. Luckily, you're a crack shot, and have your trusty rifle to hand.

The zombies start at `range` metres, and move at 0.5 metres per second. Each second, you first shoot one zombie, and then the remaining zombies shamble forwards another 0.5 metres.

If any zombies manage to get to 0 metres, you get eaten. If you run out of ammo before shooting all the zombies, you'll also get eaten. To keep things simple, we can ignore any time spent reloading.

Write a function that accepts the total number of zombies, a range in metres, and the number of bullets you have.

If you shoot all the zombies, return "You shot all X zombies."
If you get eaten before killing all the zombies, and before running out of ammo, return "You shot X zombies before being eaten: overwhelmed."
If you run out of ammo before shooting all the zombies, return "You shot X zombies before being eaten: ran out of ammo."

(If you run out of ammo at the same time as the remaining zombies reach you, return "You shot X zombies before being eaten: overwhelmed.".)

Good luck! (I think you're going to need 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 zombie_shootout(z, r, a):\n    s = min(r*2, a)\n    return f"You shot all {z} zombies." if s>=z else f"You shot {s} zombies before being eaten: { \'overwhelmed\' if s==2*r else \'ran out of ammo\' }."'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'zombie_shootout'
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: 5500