100% code, ;-)

using System;

namespace fishingBoat
{
    class Program
    {
        static void Main(string[] args)
        {
            double budget = double.Parse(Console.ReadLine());
            string season = Console.ReadLine();
            double fishers = double.Parse(Console.ReadLine());
            double fishersAmount = fishers % 2;
            double priceShip = 0.0;

            switch (season)
            {
                case "Spring": priceShip = 3000; break;
                case "Summer":
                case "Autumn": priceShip = 4200; break;
                case "Winter": priceShip = 2600; break;
                default:
                    break;
            }

            if (fishers <= 6)
            {
                priceShip = priceShip * 0.9;
            }
            else if (fishers > 6 && fishers <= 11)
            {
                priceShip = priceShip * 0.85;
            }
            else if (fishers > 12)
            {
                priceShip = priceShip * 0.75;
            }

            if (fishersAmount == 0)
            {
                if (season == "Spring")
                {
                    priceShip = priceShip * 0.95;
                }
                if (season == "Summer")
                {
                    priceShip = priceShip * 0.95;
                }
                if (season == "Winter")
                {
                    priceShip = priceShip * 0.95;
                }
            }

            double difference = Math.Abs(budget - priceShip);

            if (budget >= priceShip)
            {
                Console.WriteLine($"Yes! You have {difference:F2} leva left.");
            }
            else if (budget < priceShip)
            {
                Console.WriteLine($"Not enough money! You need {difference:F2} leva.");
            }
        }
    }
}