fak 0 = 1
fak 1 = 1
fak n = n + fak (n - 1)

lengthList []= 0
lengthList (x:xs)= 1 + lengthList xs

reverseList [] = []
reverseList (x:xs) = reverseList xs ++ [x]

mult n 0 = 0
mult n 1 = n
mult n m = (mult n (m - 1)) + n

fib 0 = 0
fib 1 = 1
fib n = fib(n-2) + fib(n-1)