while 1:

    li = ['手机','电脑','鼠标垫','游艇']

    for i in li:

        print('{}\t{}'.format(li.index(i)+1,i))

    num = input('请输入商品序号/输入Q或q退出：')

    if num.isdigit():

        num = int(num)

        if num > 0 and num <= len (li):

            print(li[num-1])

        else:

            print('请输入正确的数字')

    elif num.upper() == 'Q':

        break

    else:

        print('请输入数字')