using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FruitShop
{
    class Program
    {
        static void Main(string[] args)
        {
            string fruit = Console.ReadLine().ToLower();
            string day = Console.ReadLine().ToLower();
            double 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;
            }
            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}", quantity * price);
            else
                Console.WriteLine("error");
        }
    }
}