import java.util.Scanner;

public class SmallShop {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String product = scanner.nextLine().toLowerCase();
        String town = scanner.nextLine().toLowerCase();
        double quantity = Double.parseDouble(scanner.nextLine());

        if (town.equals("sofia")) {
            if (product.equals("coffee")) {
                System.out.println(quantity * 0.5);
            } else if (product.equals("water")) {
                System.out.println(quantity * 0.8);
            } else if (product.equals("beer")) {
                System.out.println(quantity * 1.2);
            } else if (product.equals("sweets")) {
                System.out.println(quantity * 1.45);
            } else if (product.equals("peanuts")) {
                System.out.println(quantity * 1.6);


            } else if (town.equals("plovdiv")) {
                if (product.equals("coffee")) {
                    System.out.println(quantity * 0.4);
                } else if (product.equals("water")) {
                    System.out.println(quantity * 0.7);
                } else if (product.equals("beer")) {
                    System.out.println(quantity * 1.15);
                } else if (product.equals("sweets")) {
                    System.out.println(quantity * 1.3);
                } else if (product.equals("peanuts")) {
                    System.out.println(quantity * 1.5);


                } else (town.equals("varna")) {
                    if (product.equals("coffee")) {
                        System.out.println(quantity * 0.45);
                    } else if (product.equals("water")) {
                        System.out.println(quantity * 0.7);
                    } else if (product.equals("beer")) {
                        System.out.println(quantity * 1.1);
                    } else if (product.equals("sweets")) {
                        System.out.println(quantity * 1.35);
                    } else if (product.equals("peanuts")) {
                        System.out.println(quantity * 1.55);
                    }
                }
            }
        }
    }
}