"""Factorial of n (iterative implementation).

@author: Pablo Trinidad <github.com/pablotrinidad>
"""


def factorial(n):
    """Algorithm implementation."""
    r = 1
    while n > 0:
        r = r * n
        n = n - 1
    return r

n = int(input("Enter an integer n to compute its factorial: "))
print(str(n) + "! = " + str(factorial(n)))