using System;
using System.Collections.Generic;

namespace FruitShop
{
    class FruitShop
    {
        static void Main(string[] args)
        {
            var product = Console.ReadLine();
            var day = Console.ReadLine();
            var quantity = double.Parse(Console.ReadLine());
            var workDays = new HashSet<string>()
            {
                "Monday","Tuesday","Wednesday","Thursday","Friday"
            };

            var weekend = new HashSet<string>()
            {
                "Saturday","Sunday"
            };

            var workDayPricing = FillPricing(2.50, 1.20, 0.85, 1.45, 2.70, 5.50, 3.85);
            var weekendPricing = FillPricing(2.70, 1.25, 0.90, 1.60, 3.00, 5.60, 4.20);

            if (workDays.Contains(day))
            {
                if (workDayPricing.ContainsKey(product))
                {
                    Console.WriteLine("{0:F2}", workDayPricing[product] * quantity);
                }
                else
                {
                    Console.WriteLine("error");
                }
            }
            else if (weekend.Contains(day))
            {
                if (weekendPricing.ContainsKey(product))
                {
                    Console.WriteLine("{0:F2}", weekendPricing[product] * quantity);
                }
                else
                {
                    Console.WriteLine("error");
                }
            }
            else
            {
                Console.WriteLine("error");
            }
        }

        private static Dictionary<string, double> FillPricing(double d1, double d2, double d3,
            double d4, double d5, double d6, double d7)
        {
            var pricing = new Dictionary<string, double>();
            pricing.Add("banana", d1);
            pricing.Add("apple", d2);
            pricing.Add("orange", d3);
            pricing.Add("grapefruit", d4);
            pricing.Add("kiwi", d5);
            pricing.Add("pineapple", d6);
            pricing.Add("grapes", d7);

            return pricing;
        }
    }
}