def det(a: list) -> int:
	"""
	Calculates the determinant of a 2x2 Matrix, via the shortcut
	(a*d) - (b*c)

	:param a: The matrix A.
	:return: The determinant.
	"""

	d= (a[0][0] * a[1][1]) - (a[0][1] * a[1][0])
	return d