def compute_in_degrees(digraph):
	"""
	Compute the in-degrees for the nodes in digraph
	and store them in a dictionary
	"""
	in_degrees = {}
	for key_i in digraph:
		degree = 0
		for key_j in digraph:
			if key_i in digraph[key_j]:
				degree += 1
		in_degrees[key_i] = degree
	return in_degrees