using System; 

    public class Program 

{   public static void Main()

    {

            double P = Math.PI; Console.WriteLine(" пи = " + "{0:F12}", +P); // Console.WriteLine("");

            Console.WriteLine(" Search > F [MHz]        (Enter>1) {input L & C} = ");

            Console.WriteLine(" Search > L [microHenry] (Enter>2) {input F & C} = ");

            Console.WriteLine(" Search > C [pF]         (Enter>3) {input F & L} = ");

            Console.Write(" Search [ F || L || C ] > input { 1 or 2 or 3 } => ");

            int A = int.Parse(s: Console.ReadLine());

            while (A < 1 || A > 3)

            {

                Console.WriteLine(" input 1 or 2 or 3");

                A = int.Parse(Console.ReadLine());

            }

            Console.WriteLine(" You Entered > " + A);

            if (A != 1)

            {

                if (A == 2)

                {

                    Console.WriteLine(" Search L");

                    Console.Write(" Input F [MHz]  => ");

                    int F = int.Parse(Console.ReadLine());

                    Console.Write(" Input C [pF]  => ");

                    int C = int.Parse(Console.ReadLine());

                    double L = 1 / (4 * P * P * F * F * C);

                    Console.WriteLine(" L [inductance microHenry] = " + "{0:F6}", +L*1000000);

                    // System.Threading.Thread.Sleep(60000);

                }

                else if (A == 3)

                {

                    Console.WriteLine(" Search C");

                    Console.Write(" Input F [MHz] => ");

                    int F = int.Parse(Console.ReadLine());

                    Console.Write(" Input L [microHenry] => ");

                    int L = int.Parse(Console.ReadLine());

                    double C = 1 / (4 * P * P * F * F * L);

                    Console.WriteLine(" Capacity [pF] = " + "{0:F6}", +C * 1000000);

                    // System.Threading.Thread.Sleep(60000);

                }

            }

            else

            {

                Console.WriteLine(" Search F");

                Console.Write(" Input C [pF] => ");

                int C = int.Parse(Console.ReadLine());

                Console.Write(" Input L [microHenry] => ");

                int L = int.Parse(Console.ReadLine());

                double F = 1 / (2 * P * Math.Sqrt(C * L));

                Console.WriteLine(" Frequency [MHz] = " + "{0:F6}", +F * 1000);

                // System.Threading.Thread.Sleep(60000);

            }

    }

}