using System;

public class Program

{

    public abstract class Shape

    {

        private string name;

        public Shape(string inName){

            this.name = inName;

        }

       public abstract double Area { get; }

​

       public abstract double Perimeter { get; }

​

       public override string ToString() => GetType().Name;

​

       public static double GetArea(Shape shape) => shape.Area;

​

       public static double GetPerimeter(Shape shape) => shape.Perimeter;

    }

    public class Square : Shape

    {

        public Square(): base("square"){

            Side = 0;

        }

       public Square(double length): base("square")

       {

           if (length < 0)

           {

               throw new System.ArgumentException("Parameter cannot be less than zero");

           }

          Side = length;

       }

​

       public double Side { get; }  

​

       public override double Area => Math.Pow(Side, 2); 

​

       public override double Perimeter => Side * 4;

​

       public double Diagonal => Math.Round(Math.Sqrt(2) * Side, 2); 

    }

    public static void Main()

    {       

        Square result = new Square(10);

        Console.WriteLine(result.Perimeter);

        Console.WriteLine(Square.GetPerimeter(result));

    }

}