public class MyClass {
    public static void main(String args[]) {
        java.util.Scanner scanner = new java.util.Scanner(System.in);
        String product = scanner.nextLine();
        String city = scanner.nextLine();
        double quantity = scanner.nextDouble();

        switch(product) {
            case "coffee" :
                switch(city) {
                    case "Varna" :
                        System.out.print(0.45 * quantity);
                        break;
                    case "Sofia" :
                        System.out.print(0.5 * quantity);
                        break;
                    case "Plovdiv" :
                        System.out.print(0.4 * quantity);
                        break;
                } break;
            case "water" :
                switch(city) {
                    case "Varna" :
                        System.out.print(0.7 * quantity);
                        break;
                    case "Sofia" :
                        System.out.print(0.8 * quantity);
                        break;
                    case "Plovdiv" :
                        System.out.print(0.7 * quantity);
                        break;
                } break;
            case "beer" :
                switch(city) {
                    case "Varna" :
                        System.out.print(1.1 * quantity);
                        break;
                    case "Sofia" :
                        System.out.print(1.2 * quantity);
                        break;
                    case "Plovdiv" :
                        System.out.print(1.15 * quantity);
                        break;
                } break;
            case "sweets" :
                switch(city) {
                    case "Varna" :
                        System.out.print(1.35 * quantity);
                        break;
                    case "Sofia" :
                        System.out.print(1.45 * quantity);
                        break;
                    case "Plovdiv" :
                        System.out.print(1.3 * quantity);
                        break;
                } break;
            case "peanuts" :
                switch(city) {
                    case "Varna" :
                        System.out.print(1.55 * quantity);
                        break;
                    case "Sofia" :
                        System.out.print(1.6 * quantity);
                        break;
                    case "Plovdiv" :
                        System.out.print(1.5 * quantity);
                        break;
                } break;
        }
    }
}