import Prelude hiding (take, drop)

take :: Int -> [a] -> [a]
take 0 _ = []
take n [] = []
take n (x:xs) = x: take (n - 1) xs

drop :: Int -> [a] -> [a]
drop 0 xs = xs
drop n [] = []
drop n (x:xs) = drop (n - 1) xs

takeDrop :: Int -> [a] -> ([a],[a])
takeDrop 0 xs = ([],xs)
takeDrop n [] = ([],[])
takeDrop n (x:xs) = (x:first,second)
	where
		(first,second) = takeDrop (n - 1) xs


--is_elem_of :: a -> [a] -> Bool
is_elem_of element [] = False
is_elem_of element (x:xs) = (x == element) || (is_elem_of element xs)

intersection [] _ = []
intersection _ [] = []
intersection (x:xs) (y:ys)
	|is_elem_of x (y:ys) = x: intersection xs (y:ys)
	|otherwise = intersection xs (y:ys)

func [] ys _ _ = []
func (x:xs) ys (z:zs) xs_lst
	|is_elem_of x inter = z: func xs ys zs xs_lst
	|otherwise = x: func xs ys zs xs_lst
		where
			inter = intersection xs_lst ys

main_func xs ys zs = func xs ys zs xs