using System;
 
 
namespace Program
{
    class program
    {
        static void Main()
        {
            double n1 = 0, n2 = 0, n3 = 0;
            Method(ref n1, ref n2, ref n3);
 
        }
        static public void Method(ref double n1, ref double n2, ref double n3)
        {
            Console.Write("A=?");
            double a = int.Parse(Console.ReadLine());
            double sum = 0;
            double y = 0;
            int count = 0;
            for (int x = 2; x < 13; x++)
            {
                y = Math.Cos(x / a) + x / (a - 2);
 
                count++;
                if (count == 1) {
                    n1 = y;
                    Console.WriteLine("n1 = {0}", y);
                }
                if (count == 2)
                {
                    n2 = y;
                    Console.WriteLine("n2 = {0}", y);
                }
                if (count == 3)
                {
                    n3 = y;
                    Console.WriteLine("n3 = {0}", y);
                }
                sum += y;
            }
            Console.WriteLine("{0} - сумма  ", sum);
        }
    }
 
 
}