product_list=[("iPhone XS Max 256G",11000),('MacBook Pro 512G',19000),('Bike',800),("Apple Watch Series 4",3500),("Coffee",30),("Alex Python Book",60)]
shopplist_list=[]
salary=input("请输入你的收入:")
if salary.isdigit():
    salary=int(salary)
    while True:
        for index,item in enumerate(product_list):
            print(index,item)
        user_choice=input("你选择要买:").strip()
        if user_choice.isdigit():
            user_choice=int(user_choice)
            if user_choice<len(product_list) and user_choice>=0:
                p_item=product_list[user_choice]
                if p_item[1]<=salary:
                    shopplist_list.append(p_item)
                    salary=salary-p_item[1]
                    print("added %s into shopping cart,you current balance is %s"%(p_item,salary))
                else:
                    print("你的余额只剩[%s]啦，余额不足"%salary)
            else:
                print("product code [%s] is not exist!"%user_choice)
        elif user_choice=="q":
            print("---shopping list----")
            for p in shopplist_list:
                print(p[0])
            print("已经购买:",shopplist_list,"\n还剩",salary,"元")
            break
        else:
            print("invalid option")
            print("已经购买:", shopplist_list, "\n还剩", salary, "元")
            break