C#计算圆的周长和面积(从控制台读入半径)

using System;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            float a = float.Parse(Console.ReadLine());
            float cir = 2 * a * 3.1415f;
            float area = a * a * 3.1415f;
            cir = (float)Math.Round((float)cir, 2);
            area= (float)Math.Round((float)area, 2);
            Console.Write("Circle:{0},Area:{1}",cir,area);
        }
    }
}