Dee is lazy but she's kind and she likes to eat out at all the nice restaurants and gastropubs in town. To make paying quick and easy she uses a simple mental algorithm she's called The Fair %20 Rule. She's gotten so good she can do this in a few seconds and it always impresses her dates but she's perplexingly still single. Like you probably. 

This is how she does it:

 - She rounds the price `P` at the tens place e.g:
   - 25 becomes 30
   - 24 becomes 20
   - 5 becomes 10
   - 4 becomes 0
 - She figures out the base tip `T` by dropping the singles place digit e.g:
   - when `P = 24` she rounds to 20 drops 0 `T = 2`
   - `P = 115` rounds to 120 drops 0 `T = 12`
   - `P = 25` rounds to 30 drops 0 `T = 3`
   - `P = 5` rounds to 10 drops 0 `T = 1`
   - `P = 4` rounds to 0 `T = 0`
 - She then applies a 3 point satisfaction rating `R` to `T` i.e:
   - When she's satisfied: `R = 1` and she'll add 1 to `T`
   - Unsatisfied: `R = 0` and she'll subtract 1 from `T`
   - Appalled: `R = -1` she'll divide `T` by 2, **rounds down** and subtracts 1
 
## Your Task

Implement a method `calc_tip` that takes two integer arguments for price `p` 

where `1 <= p <= 1000` and a rating `r` which is one of `-1, 0, 1`.

The return value `T` should be a non negative integer.

*Note: each step should be done in the order listed.*

Dee always politely smiles and says "Thank you" on her way out. Dee is nice. Be like Dee.

```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 calc_tip(p, r):\n    if p%10<5: p-=p%10\n    else: p+=(10-p%10)\n    t=p/10\n    if r==1: t+=1\n    elif r==0: t-=1\n    elif r==-1: t=int(t/2)-1\n    return max(t,0)\n    \n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'calc_tip'
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: 5568