computeOctaves (x:xs) ys 
    | elem x ys = 1 + computeOctaves xs (delete x ys)
    | otherwise = computeOctaves xs ys
computeOctaves (x:xs) ys 
    | elem x ys = 1 + computeOctaves xs (delete x ys)
    | otherwise = computeOctaves xs ys
computeOctaves (x:xs) ys 
    | elem x ys = 1 + computeOctaves xs (delete x ys)
    | otherwise = computeOctaves xs ys