using System;

public class Program

{

    public static void Main()

    {

        double basePrice;

        Console.WriteLine(@"

            Items:

            - coffee

            - water

            - beer

            - sweets

            - peanuts

        ");

        Console.WriteLine("Pick an item: ");

        string item = Console.ReadLine().ToLower();

        Console.WriteLine(@"

            Locations:

            - Sofia

            - Plovdiv

            - Varna

        ");

        Console.WriteLine("Pick a location: ");

        string location = Console.ReadLine().ToLower();

        Console.WriteLine("Quantity: ");

        int quantity = Int32.Parse(Console.ReadLine());

        // coffee

        if(item == "coffee" && location == "sofia") basePrice = 0.50;

        else if(item == "coffee" && location == "plovdiv") basePrice = 0.40;

        else if(item == "coffee" && location == "varna") basePrice = 0.45;

        // water

        else if(item == "water" && location == "sofia") basePrice = 0.80;

        else if(item == "water" && location == "plovdiv") basePrice = 0.70;

        else if(item == "water" && location == "varna") basePrice = 0.70;

        // beer

        else if(item == "beer" && location == "sofia") basePrice = 1.20;

        else if(item == "beer" && location == "plovdiv") basePrice = 1.15;

        else if(item == "beer" && location == "varna") basePrice = 1.10;

        // sweets

        else if(item == "sweets" && location == "sofia") basePrice = 1.45;

        else if(item == "sweets" && location == "plovdiv") basePrice = 1.30;

        else if(item == "sweets" && location == "varna") basePrice = 1.35;

        // peanuts

        else if(item == "peanuts" && location == "sofia") basePrice = 1.60;

        else if(item == "peanuts" && location == "plovdiv") basePrice = 1.50;

        else if(item == "peanuts" && location == "varna") basePrice = 1.55;

        // err

        else if(quantity <= 0) {

            Console.WriteLine("Error: quantity < 0");

            return;

        }

        else {

            Console.WriteLine("Error: Invalid location or item.");

            return;

        }

        Console.WriteLine("Cost: " + basePrice * quantity);

    }

}