using System;

namespace MyCompiler {
    public sealed class Circle {
      private double radius;
      
      public double Calculate(Func<double, double> op) {
        return op(radius);
      }
    }
    class Program {
        public static void Main(string[] args) {
            Circle circle = new Circle();
            Console.WriteLine("Hello world!");
            var area = circle.Calculate(r => 2 * 3.14 * 10);//Need to pass lamba function
            //var area = circle.Calculate(area());
            Console.WriteLine("area {0}", area);
        }
       
    }
}