






import os
from typing import Dict, List, Tuple, TypeVar, Union


UpperCAmelCase__      			=						TypeVar('''T''')

UpperCAmelCase__      			=						Union[List[T], Tuple[T, ...]]
UpperCAmelCase__      			=						Union[T, List[T], Dict[str, T]]
UpperCAmelCase__      			=						Union[str, bytes, os.PathLike]













def     a_   (__A				,       __A				,       __A				,       __A      )				->						int:



					"""simple docstring"""
					__a      ,			__a					:						Any      =					len(__A      ), len(grid[0]      )
					if (
					    min(__A				,       __A      ) < 0
					    or row == row_length
					    or col == col_length
					    or (row, col) in visit
					    or grid[row][col] == 1
					):
										return 0
					if row == row_length - 1 and col == col_length - 1:
										return 1

					visit.add((row, col)      )

					__a					:						Dict      =					0
					count += depth_first_search(__A				,       row + 1				,       __A				,       __A      )
					count += depth_first_search(__A				,       row - 1				,       __A				,       __A      )
					count += depth_first_search(__A				,       __A				,       col + 1				,       __A      )
					count += depth_first_search(__A				,       __A				,       col - 1				,       __A      )

					visit.remove((row, col)      )
					return count


if __name__ == "__main__":
			import doctest

			doctest.testmod()





