###BACKGROUND:
Jacob recently decided to get healthy and lose some weight. He did a lot of reading and research and after focusing on steady exercise and a healthy diet for several months, was able to shed over 50 pounds! Now he wants to share his success, and has decided to tell his friends and family how much weight they could expect to lose if they used the same plan he followed.

Lots of people are really excited about Jacob's program and they want to know how much weight they would lose if they followed his plan. Unfortunately, he's really bad at math, so he's turned to you to help write a program that will calculate the expected weight loss for a particular person, given their weight and how long they think they want to continue the plan.

###TECHNICAL DETAILS:
Jacob's weight loss protocol, if followed closely, yields loss according to a simple formulae, depending on gender. Men can expect to lose 1.5% of their current body weight each week they stay on plan. Women can expect to lose 1.2%. (Children are advised to eat whatever they want, and make sure to play outside as much as they can!)

###TASK:
Write a function that takes as input:
```
- The person's gender ('M' or 'F');
- Their current weight (in pounds);
- How long they want to stay true to the protocol (in weeks);
```
and then returns the expected weight at the end of the program.

###NOTES:
Weights (both input and output) should be decimals, rounded to the nearest tenth.
Duration (input) should be a whole number (integer). If it is not, the function should round to the nearest whole number.
When doing input parameter validity checks, evaluate them in order or your code will not pass final tests.

```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 lose_weight(gender, weight, duration):\n    if gender not in "MF":\n        return "Invalid gender"\n    if weight <= 0:\n        return "Invalid weight"\n    if duration <= 0:\n        return "Invalid duration"\n    \n    if gender == "M":\n        loss = 1 - 1.5 / 100\n    else:\n        loss = 1 - 1.2 / 100\n    \n    return round(weight * loss**duration, 1)'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'lose_weight'
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: 5436