# Task

Write a function that accepts `msg` string and returns local tops of string from the highest to the lowest.  
The string's tops are from displaying the string in the below way:

```

                                         7891012
                             TUWvXY      6     3
                   ABCDE     S    Z      5
           lmno    z   F     R    1      4
     abc   k  p    v   G     Q    2      3
.34..9 d...j  q....x   H.....P    3......2
125678 efghi  rstuwy   IJKLMNO    45678901

```
The next top is always 1 character higher than the previous one. 
For the above example, the solution for the `123456789abcdefghijklmnopqrstuwyxvzABCDEFGHIJKLMNOPQRSTUWvXYZ123456789012345678910123` input string is `7891012TUWvXYABCDElmnoabc34`. 

- When the `msg` string is empty, return an empty string.
- The input strings may be very long. Make sure your solution has good performance.
- The (.)dots on the sample dispaly of string are only there to help you to understand the pattern  

Check the test cases for more samples.

# Series

- [String tops](https://www.codewars.com/kata/59b7571bbf10a48c75000070)
- [Square string tops](https://www.codewars.com/kata/5aa3e2b0373c2e4b420009af)

```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 tops(msg):\n    if msg:\n        step = int(((2 * len(msg) - 1)**0.5 + 3) / 2)\n        result = [msg[n*(2*n+1)-1:2*n*(n+1)] for n in range(1, step)]\n        return "".join(reversed(result))\n    return ""\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'tops'
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: 5482