using System;

​

public class Program

{

    public static void Main()

    {

        double your_money; // Declares that "your_money" is an integer variable, use this when deciding how much the user has to pay for their products.

        string product; // Declares that the product letter codes (Like A, B, C, D) are string variables.

        int product_amount; // Declares that "product_amount" is an integer variable, use this when deciding how much of a certain product to give to the user.

        Console.WriteLine("Welcome to the Smart Vending Machine, here are our products:");

        Console.WriteLine("A: Lemon Juice - 50 Pesos");

        Console.WriteLine("B: Apple Juice - 35 Pesos");

        Console.WriteLine("C: Orange Juice - 40 Pesos");

        Console.WriteLine("D: Grape Juice - 45 Pesos");

        Console.WriteLine("What would you like to purchase? (Please use the letters mentioned to indicate the product)");

        product = Convert.ToString(Console.ReadLine()); // The letters displayed such as A, B, C, D, correspond to their own products.

        if (product != "A" && product != "B" && product != "C" && product != "D" && product != "a" && product != "b" && product != "c" && product != "d")

        {

            Console.WriteLine("Please input an available item");

            return;

        }

​

        Console.WriteLine("How much of this product do you wish to purchase?");

        product_amount = Convert.ToInt32(Console.ReadLine()); // The number here (which should be 1 OR above) will be multiplied to the price.

        if (product_amount <= 0)

        {

            Console.WriteLine("Please input a number higher than 0");

            return;

        }

​

        Console.WriteLine("How much money would you like to use to purchase the product?");

        your_money = Convert.ToDouble(Console.ReadLine()); // This number will be entirely up to the user.

        if (your_money <= 0)

        {

            Console.WriteLine("Please input a number higher than 0");

            return;

        }

​

        if (product == "A" || product == "a") // Product A: Lemon Juice for 50 Pesos

        {

            int sumA = (50 * product_amount); // SumA/B/C/D is the initial calculation to multiply the price of the product to the number of products they wish to buy.

            double sumA2 = (your_money - sumA); // SumA2/B2/C2/D2 is the final calculation to subtract the user's money to the TOTAL price of the product (which is the single price multiplied by the number of products they wish to buy)

            if (sumA2 > 0)

            {

                Console.WriteLine("Your change is " + sumA2 + " pesos, enjoy your drink!");

            }

            else if (sumA2 < 0)

            {

                Console.WriteLine("Sorry, you cannot purchase the item. Your funds have been returned to you.");

            }

            else if (sumA2 == 0)

            {

                Console.WriteLine("You have paid the exact amount for the transaction, enjoy your drink!");

            }

        }

        else if (product == "B" || product == "b") // Product B: Apple Juice for 50 Pesos

        {

            int sumB = (35 * product_amount);

            double sumB2 = (your_money - sumB);

            if (sumB2 > 0)

            {

                Console.WriteLine("Your change is " + sumB2 + " pesos, enjoy your drink!");

            }

            else if (sumB2 < 0)

            {

                Console.WriteLine("Sorry, you cannot purchase the item. Your funds have been returned to you.");

            }

            else if (sumB2 == 0)

            {

                Console.WriteLine("You have paid the exact amount for the transaction, enjoy your drink!");

            }

        }

        else if (product == "C" || product == "c") // Product C: Orange Juice for 40 Pesos

        {

            int sumC = (40 * product_amount);

            double sumC2 = (your_money - sumC);

            if (sumC2 > 0)

            {

                Console.WriteLine("Your change is " + sumC2 + " pesos, enjoy your drink!");

            }

            else if (sumC2 < 0)

            {

                Console.WriteLine("Sorry, you cannot purchase the item. Your funds have been returned to you.");

            }

            else if (sumC2 == 0)

            {

                Console.WriteLine("You have paid the exact amount for the transaction, enjoy your drink!");

            }

        }

        else if (product == "D" || product == "d") // Product D: Grape Juice for 45 Pesos

        {

            int sumD = (45 * product_amount);

            double sumD2 = (your_money - sumD);

            if (sumD2 > 0)

            {

                Console.WriteLine("Your change is " + sumD2 + " pesos, enjoy your drink!");

            }

            else if (sumD2 < 0)

            {

                Console.WriteLine("Sorry, you cannot purchase the item. Your funds have been returned to you.");

            }

            else if (sumD2 == 0)

            {

                Console.WriteLine("You have paid the exact amount for the transaction, enjoy your drink!");

            }

        }

    }

}