Untitled

using System;

namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Введите X: ");
            double X = double.Parse(Console.ReadLine());

            Console.Write("Введите Y: ");
            double Y = double.Parse(Console.ReadLine());

            Console.Write("Введите N: ");
            double N = double.Parse(Console.ReadLine());

            double result = 1.0;
            int s = 1;

            for (int i = 1; i <= N; i++)
            {
                double term = 0.0;
                double f = 1.0;

                for (int j = 1; j <= 2 * i - 1; j++)
                {
                    f *= j;
                }

                if (i % 2 == 1)
                    term = (Math.Pow(X, i) - Math.Pow(Math.Cos(Y), i)) / f;
                else
                    term = (Math.Pow(Y, i) + Math.Pow(Math.Cos(X), i)) / f;

                result += s * term;
                s *= -1;
            }

            Console.WriteLine($"Результат: {Math.Round(result, 2)}");
        }
    }
}