#阶乘
sums = 1
n = input("请输入一个整数：")
'''
if not n.isalnum():
n1 = input("是否重新输入？Y or N")
if n1 == 'Y':
n = eval(input("请输入一个整数："))
else:
pass
else:
print("计算%s的阶乘！"%n)
n = eval(n)
for i in range(1,n):
sums *= i
'''
sT3 = time.perf_counter()
def isscalar(str):
try:
float(str)
except ValueError:
return False
else:
return True
if isscalar(n):
ni = eval(n)
for i in range(1, ni):
sums *= i
print("计算%d的阶乘是：%d"%(ni,sums))
#break
else:
print("请输入一个整数！")
eT3 = time.perf_counter()
t3 =eT3 - sT3
print("计算%d的阶乘耗时：%.6f"%(ni,t3))