import math
while True:
 n = int(input("请输入要求的阶乘的数:"))
 if n == 0:
 print(n,'的阶乘是:',1)
 elif n <= 0:
 print('输入有误,请输入大于0的数')
 continue
 else:
 print(n,'的阶乘是:',math.factorial(n))
 break