using static System.Console;

using static System.Math;

using static MathUtil;

​

public class Program {

    public static void Main() {

        WriteLine(DegreeToRadian(45));

        WriteLine(RadianToDegree(0.785398163397448));

    }

}

​

public static class MathUtil {

    public static double DegreeToRadian(double angle) => PI * angle / 180.0;

    public static double RadianToDegree(double angle) => angle * (180.0 / PI);

}