# Python program to display the factorial(n) using recursive functions
# factorial(n) = n * n-1 * n-2 * ... * 1; factorial of zero = 1

def recur_factorial(n):
   """Recursive function to calculate factorial"""
   if n == 0 or n == 1:
       return 1
   else:
       return(n * recur_factorial(n-1))

# Take input from the user
num = int(input("Enter a number greater than or equal to 1: "))

# check if the number is valid
if num < 0:
   print("Please enter a positive integer.")
else:
	print(str(num) + " factorial is: ")
	print(recur_factorial (num))