#
# Compute the value of n-factorial using recursion.
#
# Parameters:
#   n: the integer for which the factorial is computed
#
# Returns: n-factorial
#
def factorial(n):
  if n == 0:
    # Base case
    return 1
  else:
    # Recursive case
    return n * factorial(n - 1)

#
# Demonstrate the recursive factorial function.
#
a = int(input("Enter a non-negative integer: "))
f = factorial(a)
print(f"{a} factorial is equal to {f}")