#程序段1

def fac (n):

    s = 1

   for i in range(1, n+1):

      s =s*i

   return s

print(fac(5))

#程序段2

def fac (n):

    if n == 1:

        return 1

    else:

        return n *fac (n - 1)   #①

print(fac(5))