#write a program that reads a positive integer n, and finds 1*2*3..*n=n! 
#called n factorial
#compare results of your calculations with the built-in function factorial

#example: n=3, n!=1*2*3=6; n=5, n!=1*2*3*4*5=120

import math 

n=int(input("enter positive n "))

if(n>0):
	i=1
	factorial=1
	while(i<=n):
		factorial=factorial*i
		print("factorial in iteration",i,"is",factorial)
		i=i+1	
	print("final result of",n,"! = ",factorial)
	print("factorial using built-in function is", math.factorial(n))
else:
	print("invalid input")