# The Problem

Dan, president of a Large company could use your help. He wants to implement a system that will switch all his devices into offline mode depending on his meeting schedule. When he's at a meeting and somebody texts him, he wants to send an automatic message informing that he's currently unavailable and the time when he's going to be back.

# What To Do

Your task is to write a helper function `checkAvailability` that will take 2 arguments:

* schedule, which is going to be a nested array with Dan's schedule for a given day. Inside arrays will consist of 2 elements - start and finish time of a given appointment,

* *currentTime* - is a string with specific time in hh:mm 24-h format for which the function will check availability based on the schedule.
  * If no appointments are scheduled for `currentTime`, the function should return `true`. If there are no appointments for the day, the output should also be `true`
  *  If Dan is in the middle of an appointment at `currentTime`, the function should return a string with the time he's going to be available.
  
  
# Examples
`checkAvailability([["09:30", "10:15"], ["12:20", "15:50"]], "11:00");`
should return `true`

`checkAvailability([["09:30", "10:15"], ["12:20", "15:50"]], "10:00");`
should return `"10:15"`

If the time passed as input is *equal to the end time of a meeting*, function should also return `true`.
`checkAvailability([["09:30", "10:15"], ["12:20", "15:50"]], "15:50");`
should return `true`

*You can expect valid input for this kata*

```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 check_availability(schedule, current_time):\n    return next((stop for start, stop in schedule if start <= current_time < stop), True)'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'check_availability'
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: 5618