def fibonacci_rec(n):
    if n <= 1:
        n
    else:
        fibonacci_rec(n - 1) + fibonacci_rec(n - 2)


def fibonacci_it(n):
    if n <= 1:
        n
    else:
        fib = 1
        prev = 1
        i = 2
        while i < n:
            temp = fib
            fib = fib + prev
            prev = temp
            i++
        fib