while 1:      s = input('请输入一个数：')   s = int(s)   if s == 2:      print('质数')   else:      if s == 0 or s == 1:         print('都不是')      else:             u = s - 2         h = 1         p = 1         while u:            h = h + 1            if s % h == 0:               p = 1               break            else:               p = 0            u = u - 1         if p:            print('合数')         else:            print('质数')