diff --git a/Model/Student.cs b/Model/Student.cs
index 4b95454..aab7197 100644
--- a/Model/Student.cs
+++ b/Model/Student.cs
@@ -11,5 +11,6 @@ namespace Spg.BasicDemo.Model {
         public string FirstName { get; set; }
         public string LastName { get; set; }
         public long SozNumber { get; set; }
+        public int Id { get; internal set; }
     }
 }
diff --git a/Program.cs b/Program.cs
index 34c8db2..e99ce78 100644
--- a/Program.cs
+++ b/Program.cs
@@ -4,24 +4,44 @@
 using Spg.BasicDemo.Model;
 using System.Reflection;
 
-string s = "Hello, world!";
+internal class Program {
+    private static void Main(string[] args) {
+        string s = "Hello, world!";
 
-Console.WriteLine(s);
+        Console.WriteLine(s);
 
-Student student = new Student();
-student.FirstName = "Martin";
-student.LastName = "Schrutek";
-student.Id = 1;
+        
+        Student student = new Student();
+        student.FirstName = "Martin";
+        student.LastName = "Schrutek";
+        student.Id = 1;
 
-student.Id.ToString();
+        student.Id.ToString();
 
-bool isEqual = student.Equals(new Student());
+        bool isEqual = student.Equals(new Student());
 
 
-// Reflections
-PropertyInfo[] properties = student.GetType().GetProperties();
+        // Reflections
+        PropertyInfo[] properties = student.GetType().GetProperties();
 
-foreach (PropertyInfo property in properties) {
-    Console.Out.WriteLine(property.Name);
-}
+        foreach (PropertyInfo property in properties) {
+            Console.Out.WriteLine(property.Name);
+        }
 
+        int? e = null;
+        int? f = null;
+        int g = 0;
+
+        Console.WriteLine(e ?? f ?? 5);
+        g = e ?? 0;
+
+        Console.WriteLine(g);
+
+        //string s3 = null;
+        string s3 = "Goodbye, world!";
+        Console.WriteLine($"Length = {s3?.Length ?? 0}");
+
+        bool y = 5 == 5 ? true : false;
+        Console.WriteLine(y);
+    }
+}
\ No newline at end of file
diff --git a/bin/Debug/net6.0/Spg.BasicDemo.dll b/bin/Debug/net6.0/Spg.BasicDemo.dll
index c4298c8..6397ced 100644
Binary files a/bin/Debug/net6.0/Spg.BasicDemo.dll and b/bin/Debug/net6.0/Spg.BasicDemo.dll differ
diff --git a/bin/Debug/net6.0/Spg.BasicDemo.pdb b/bin/Debug/net6.0/Spg.BasicDemo.pdb
index d9c4684..22c85a8 100644
Binary files a/bin/Debug/net6.0/Spg.BasicDemo.pdb and b/bin/Debug/net6.0/Spg.BasicDemo.pdb differ
diff --git a/obj/Debug/net6.0/Spg.BasicDemo.csproj.CoreCompileInputs.cache b/obj/Debug/net6.0/Spg.BasicDemo.csproj.CoreCompileInputs.cache
index b0adac0..a5c0c0d 100644
--- a/obj/Debug/net6.0/Spg.BasicDemo.csproj.CoreCompileInputs.cache
+++ b/obj/Debug/net6.0/Spg.BasicDemo.csproj.CoreCompileInputs.cache
@@ -1 +1 @@
-f859f888a51e1a4435b0c78c05e2d5e0bb4e7cbc
+894e3e29235fe86dbebdadba5ec62bc46a878ace
diff --git a/obj/Debug/net6.0/Spg.BasicDemo.dll b/obj/Debug/net6.0/Spg.BasicDemo.dll
index c4298c8..6397ced 100644
Binary files a/obj/Debug/net6.0/Spg.BasicDemo.dll and b/obj/Debug/net6.0/Spg.BasicDemo.dll differ
diff --git a/obj/Debug/net6.0/Spg.BasicDemo.pdb b/obj/Debug/net6.0/Spg.BasicDemo.pdb
index d9c4684..22c85a8 100644
Binary files a/obj/Debug/net6.0/Spg.BasicDemo.pdb and b/obj/Debug/net6.0/Spg.BasicDemo.pdb differ
diff --git a/obj/Debug/net6.0/ref/Spg.BasicDemo.dll b/obj/Debug/net6.0/ref/Spg.BasicDemo.dll
index a3433c4..596a501 100644
Binary files a/obj/Debug/net6.0/ref/Spg.BasicDemo.dll and b/obj/Debug/net6.0/ref/Spg.BasicDemo.dll differ
diff --git a/obj/Debug/net6.0/refint/Spg.BasicDemo.dll b/obj/Debug/net6.0/refint/Spg.BasicDemo.dll
index a3433c4..596a501 100644
Binary files a/obj/Debug/net6.0/refint/Spg.BasicDemo.dll and b/obj/Debug/net6.0/refint/Spg.BasicDemo.dll differ