einfuegen a xs
	| elem a xs = xs
	| otherwise = a:xs

entfernen a [] = []
entfernen a (x:xs)
	| a == x = xs
	| otherwise = x:(entfernen a xs)

einfach [] y = y
einfach (x:xs) y
	| elem x y = einfach xs (entfernen x y)
	| otherwise = x:einfach xs y