using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp4
{
    class Program
    {
        static void Main(string[] args)
        {
            var fruit = Console.ReadLine();
            var dayOfWeek = Console.ReadLine();
            var calculation = double.Parse(Console.ReadLine());

            string[] workdaysDays = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" };
            string[] weekendDays = { "Saturday", "Sunday" };
            string[] realFuits = { "banana", "apple", "orange", "grapefruit", "kiwi", "pineapple", "grapes" };
            double[] workdaysPrice = { 2.50, 1.20, 0.85, 1.45, 2.70, 5.50, 3.85 };
            double[] weekendPrice = { 2.70, 1.25, 0.90, 1.60, 3.00, 5.60, 4.20 };

            Dictionary<string, double> workdays = new Dictionary<string, double>();
            for (int i = 0; i < realFuits.Length; i++) workdays.Add(realFuits[i], workdaysPrice[i]);

            Dictionary<string, double> weekend = new Dictionary<string, double>();
            for (int i = 0; i < realFuits.Length; i++) weekend.Add(realFuits[i], weekendPrice[i]);

            if (workdaysDays.Any(dayOfWeek.Contains)) TryParse(fruit, calculation, workdays);
            else if (weekendDays.Any(dayOfWeek.Contains)) TryParse(fruit, calculation, weekend);
            else Console.WriteLine("error");
        }
        private static void TryParse(string fruit, double calculation, Dictionary<string, double> workdays)
        {
            try
            {
                var price = workdays[fruit];
                Console.WriteLine($"{price * calculation:f2}");
            }
            catch (Exception)
            {
                Console.WriteLine("error");
            }
        }
    }
}