تبلیغات
 static void Main(string[] args)
        {
            int a = Convert.ToInt32(Console.ReadLine());
            circle s1 = new circle();
            circle_2 s2 = new circle_2();
            s1.sa = a;
            s2.sa = a;
            Console.WriteLine(s1.area());
            Console.WriteLine(s2.area());
           
        }