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

namespace FruitShop
{
    class FruitShop
    {
        static void Main(string[] args)
        {
            string fruit = Console.ReadLine().ToLower();
            string day = Console.ReadLine().ToLower();
            double quantity = double.Parse(Console.ReadLine());

            if (day == "sunday" || day == "saturday")
            {
                switch (fruit)
                {
                    case "banana": Console.WriteLine($"{quantity * 2.70:F2}");break;
                    case "apple": Console.WriteLine($"{quantity * 1.25:F2}"); break;
                    case "orange": Console.WriteLine($"{quantity * 0.90:F2}"); break;
                    case "grapefruit": Console.WriteLine($"{quantity * 1.60:F2}"); break;
                    case "kiwi": Console.WriteLine($"{quantity * 3.00:F2}"); break;
                    case "pineapple": Console.WriteLine($"{quantity * 5.60:F2}"); break;
                    case "grapes": Console.WriteLine($"{quantity * 4.20:F2}"); break;
                    default:
                        Console.WriteLine("error");
                        break;
                }
            }
            else if (day == "monday" || day == "tuesday" || day == "wednesday" || day == "thursday" || day == "friday")
            {
                switch (fruit)
                {
                    case "banana": Console.WriteLine($"{quantity * 2.50:F2}"); break;
                    case "apple": Console.WriteLine($"{quantity * 1.20:F2}"); break;
                    case "orange": Console.WriteLine($"{quantity * 0.85:F2}"); break;
                    case "grapefruit": Console.WriteLine($"{quantity * 1.45:F2}"); break;
                    case "kiwi": Console.WriteLine($"{quantity * 2.70:F2}"); break;
                    case "pineapple": Console.WriteLine($"{quantity * 5.50:F2}"); break;
                    case "grapes": Console.WriteLine($"{quantity * 3.85:F2}"); break;
                    default:
                        Console.WriteLine("error");
                        break;
                }
            }
            else
            {
                Console.WriteLine("error");
            }
        }
    }
}