#crea una lista según la cantidad de elementos que el usuario quiera
shopping = []#lista vacía
entrada = input("how many items of shopping are needed? ")
subtotal = 0
off = 0.1
total= 0
if entrada.isdigit():
        for item_number in range(int(entrada)):# para variable item_number in rango de 5 elementos, del 0 al 4
                item = input("what is the item " + str(item_number) + "? ")#variable item pregunta al usuario cuál es el item que desea agregar y lista la cantidad ingresada
                if item.isalpha():
                    price = input("what is the price of "+ item + "? ")
                    if price.isdigit():
                        shopping.append(item)#agrega a lista que estaba vacía shopping el valor ingresado
                        subtotal = subtotal + int(price)
                        total = subtotal*(1-off)
                    else:
                        print("Please, put a valid value")
                else:
                    print("Please, put a valid value")
        print("Your list is " + str(shopping))
        print(str("There is ") + str(entrada) + str(" items in your shopping list, thanks for comming "))
        print("Your count is " + str(total) + " USD")
        print("You save " + str(subtotal-total) + " USD")
else:
    print("Please, put a valid value")