Little scheme project

The programming language scheme
Write an function maxlist that returns the maximum element in a simple list of numbers.
(maxlist '(2 5 6 3)) -> 6
Write a recursive function flatten that takes a list as an argument and returns the flat version of that list. For
example,
(flatten '(a (b c) d)) -> (a b c d)
(flatten '(((a)) (b (c)) d) -> (a b c d)
Write a maxel that returns the maximum element in an arbitrarily complex list (e.g., list that may contain lists,
which may contain lists, and so on). For example,
(maxel '(((5)) (9 (3)) 7) -> 9


I need under 24 hours