using System;

​

public struct Point3D

{

    public Point3D(double x, double y, double z)

    {

        _x = x;

        _y = y;

        _z = z;

    }

​

    private double _x;

    public double X

    {

        readonly get => _x;

        set => _x = value;

    }

​

    private double _y;

    public double Y

    {

        readonly get => _y;

        set => _y = value;

    }

​

    private double _z;

    public double Z

    {

        readonly get => _z;

        set => _z = value;

    }

​

    public readonly double Distance => Math.Sqrt(X * X + Y * Y + Z * Z);

​

    public readonly override string ToString() => $"{X}, {Y}, {Z}";

}

​

public class Program

{

    public static void Main()

    {

​

        Point3D p=new Point3D(1,2,3);

​

​

        Console.WriteLine(p);

    }

    public static void Mod(ref double  v)

    {

        v= 0;

    }

}