static void Main(string[] args)
{
// Wrong Usage!
// Person P;
// P.Age = 20;
// P.FullName = "Ali Reza Alavi";
// P.ShowInfo();
Person P1;
P1 = new Person();
P1.Age = 20;
P1.FullName = "Ali Reza Alavi";
P1.ShowInfo();
System.Console.WriteLine("\n");
Person P2 = new Person();
P2.Age = 30;
P2.FullName = "Sara Ahmadi";
P2.ShowInfo();
System.Console.WriteLine("\n");
Person P3;
P3 = P1;
P3.ShowInfo();
System.Console.WriteLine("\n");
Person P4 = P2;
P4.ShowInfo();
System.Console.WriteLine("\n");
Person P5 = P1;
P5.Age = 21;
P5.ShowInfo();
P1.ShowInfo();
System.Console.ReadLine();
}