def fact():
number=eval(input("Enter a number to get the factorial: "))
initialvalue=1
if number>0:
for number in range(number,1,-1):
initialvalue=initialvalue*number
print(initialvalue)
elif number==0:
print(1)
elif number<0:
for number in range(number, -1, 1):
initialvalue=initialvalue*number
print(-initialvalue)
fact()