Hi there! 
You have to implement the 

`String get_column_title(int num) // syntax depends on programming language`

function that takes an integer number (index of the Excel column) and returns the string represents the title of this column.

#Intro
In the MS Excel lines are numbered by decimals, columns - by sets of letters.

For example, the first column has the title "A", second column - "B", 26th - "Z", 27th - "AA". 

"BA"(53) comes after "AZ"(52), "AAA" comes after "ZZ".




Excel? Columns? More details [here](https://en.wikipedia.org/wiki/Microsoft_Excel)

#Input
It takes only one argument - column decimal index number.
Argument `num` is a natural number.

#Output
Output is the upper-case string represents the title of column. It contains the English letters: A..Z

#Errors
For cases `num < 1` your function should throw/raise `IndexError`. In case of non-integer argument you should throw/raise `TypeError`.

In Java, you should throw `Exceptions`.

Nothing should be returned in Haskell.

#Examples
Python, Ruby:
```
>>> get_column_title(52)
"AZ"
>>> get_column_title(1337)
"AYK"
>>> get_column_title(432778)
"XPEH"
>>> get_column_title()
TypeError:
>>> get_column_title("123")
TypeError:
>>> get_column_title(0)
IndexError:
```
JS, Java:
```
>>> getColumnTitle(52)
"AZ"
>>> getColumnTitle(1337)
"AYK"
>>> getColumnTitle(432778)
"XPEH"
>>> getColumnTitle()
TypeError:
>>> getColumnTitle("123")
TypeError:
>>> getColumnTitle(0)
IndexError:
```

#Hint
The difference between the 26-digits notation and Excel columns numeration that in the first system, after "Z" there are "BA", "BB", ..., while in the Excel columns scale there is a range of 26 elements: AA, AB, ... , AZ between Z and BA. 

It is as if in the decimal notation was the following order: 0, 1, 2, .., 9, 00, 01, 02, .., 09, 10, 11, .., 19, 20..29..99, 000, 001 and so on.

#Also
The task is really sapid and hard. If you're stuck - write to the discussion board, there are many smart people willing to help.

```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 = "from string import ascii_uppercase\n\ndef get_column_title(n):\n    n -= 1\n    result = []\n    while n >= 0:\n        result.append(ascii_uppercase[n % 26])\n        n = n // 26 - 1\n    if not result:\n        raise ValueError('Not a valid number.')\n    return ''.join(result[::-1])"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'get_column_title'
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: 5536