using System;

namespace Fruit_Shop
{
    class Program
    {
        static void Main()
        {
            var fruit = Console.ReadLine().ToLower();
            var day = Console.ReadLine().ToLower();
            var quantity = double.Parse(Console.ReadLine());
            var price = -1.0;

            if ((day == "monday") ||
                (day == "tuesday") ||
                (day == "wednesday") ||
                (day == "thursday") ||
                (day == "friday"))
            {
                if (fruit == "banana") { price = 2.50; }
                else if (fruit == "apple") { price = 1.20; }
                else if (fruit == "orange") { price = 0.85; }
                else if (fruit == "grapefruit") { price = 1.45; }
                else if (fruit == "kiwi") { price = 2.70; }
                else if (fruit == "pineapple") { price = 5.50; }
                else if (fruit == "grapes") { price = 3.85; }
            }

            else if ((day == "saturday") || (day == "sunday"))
            {
                if (fruit == "banana") { price = 2.70; }
                else if (fruit == "apple") { price = 1.25; }
                else if (fruit == "orange") { price = 0.90; }
                else if (fruit == "grapefruit") { price = 1.60; }
                else if (fruit == "kiwi") { price = 3.00; }
                else if (fruit == "pineapple") { price = 5.60; }
                else if (fruit == "grapes") { price = 4.20; }
            }

            if (price > 0)
            {
                Console.WriteLine("{0:f2}", price * quantity);
            }
            else
            {
                Console.WriteLine("error");
            }
        }
    }
}