# Factorial of n = n * (n-1) * (n-2) * ... * 1
# Factorial of 0 defined to be 1 

# Take input from the user
num = int(input("Please enter a positive integer: "))
numsaved = num

if num < 0:
   print("Please enter a positive integer.")
else:
	fact = 1
	while num > 0:
		fact = fact * num
		num -= 1
		
print ('Factorial of ' + str(numsaved) + ' is ' + str(fact))