while语句：
count = 0
while True:
print(count)
count += 1
if count == 10:
break
实例：
计算n！，若：n = 5；则：n! = 5 * 4 * 3 * 2 * 1
#n!
n = int(input("输入n："))
number = n
while True:
if number == 1:
break
number = number * (n-1)
n -= 1
if n <= 2:
break
print(number)