13 阶乘之和

def f(x):
      if x == 0:
           return 0
      elif x == 1:
           return 1
      else:
            return (x * f(x - 1))

while 1:
        info = int(input('>>>:'))
        print(f(info))
        info = input('还想试试吗？(输入n退出)')
        if info == 'n':
            break