def fiban(n):
    def fibIter(a, b, count):
         if count == 0:
             return b
         else:
             return fibIter(a + b, a, count - 1)

    return fibIter(1, 0, n)


fibonacchi = lambda n: n < 3 and 1 or fibonacchi(n - 1) + fibonacchi(n - 2)

def FIB(n):
    if n < 2:
        return n
    else:
        return FIB(n-1) + FIB(n-2)