ArrayList of Points Learn programming C#

using System;
using System.Collections;
namespace Point3D
{
    class Program
    {
        struct Point3D 
        {
            double x, y, z; 
        }

        static void Main(string[] args)
        {
            bool exit = false;

            ArrayList list = new ArrayList(); 
            Point3D points = new Point3D();

            string answer;
            do
            {
                Console.WriteLine("1. Add data for one point");
                Console.WriteLine("2. Display all the entered points");
                Console.WriteLine("x. Display all the entered points");
                Console.WriteLine();
                Console.Write("Enter a option: ");
                answer = Console.ReadLine();
                
                if (answer.ToLower() == "x")
                {
                    exit = true;
                }
                else if (answer == "1")
                {
                    Console.Write("Point x: ");
                    list.Add(Convert.ToInt32(Console.ReadLine()));

                    Console.Write("Point y: ");
                    list.Add(Convert.ToInt32(Console.ReadLine()));

                    Console.Write("Point z: ");
                    list.Add(Convert.ToInt32(Console.ReadLine()));
                }
            }
            while (!exit);
        }
    }
}