finished = False
while finished == False:

    #Greeting
    print("Hi, I am Marvin, your personal bot.")

    #Ask the user for a command
    command = input("How can I help? ")

    #Check for addition command

    if command == "add" or command == "plus" or command == "Add" or command == "Plus":
        print("let's add some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 + number2
        output = str(result)
        print(input1 + " + " + input2 + " = " + output)

    #Check for subtraction command

    elif command == "subtract" or command == "take" or command == "Subtract" or command == "Take":
        print("let's subtract some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 - number2
        output = str(result)
        print(input1 + " - " + input2 + " = " + output)

    #Check for division command

    elif command == "divide" or command == "Divide":
        print("let's divide some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 / number2
        output = str(result)
        print(input1 + " / " + input2 + " = " + output)

    #Check for multiply command

    elif command == "multiply" or command == "Multiply" or command == "times" or command == "Times":
        print("let's multiply some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 * number2
        output = str(result)
        print(input1 + " x " + input2 + " = " + output)


    #Check for average command

    elif command == "average" or command == "Average":
        print("let's work out an average")
        how_many = input("How many numbers would you like to average?> ")
        how_many = int(how_many)
        total = 0
        number_list=[]
        for number_count in range(how_many):
            number = input("Enter number " + str(number_count+1) + "> ")
            total = total + int(number)
            number_list.append(number)
        result = total / how_many
        print("here are the numbers you wanted to average")
        for item in number_list:
            print(item)
        print("the average of those numbers = " +str(result))

    #Check for shopping list command

    elif command == "shopping" or command == "Shopping":
        #Create a shopping list calculator with given number of items based on user input and display it on screen

        shopping =[]

        how_many = input("how many items of shopping do you have? ")
        how_many_items = int(how_many)

        for item in range(how_many_items):
            new_item = input("Enter item number " + str(item+1) + " in the shopping list > ")
            shopping.append(new_item)

        #Print out the items

        for item in shopping:
            print(item)

        print("You added " + how_many + " items to the list")

        print("now let's calculate how much that will cost you!")

        total_cost=0

        for item in shopping:
            item_cost=input("how much is the item " + item + " in £ ? >")
            total_cost=total_cost+float(item_cost)

        print("the total cost of your shopping is £" + str(total_cost))


    elif command == "bye" or command == "Bye":
        finished = True


    #Error handling for unknown commands

    else:
        print("Sorry, I don't understand")


print("Bye! Hope I was helpful!")