What will be the output of the following C# code?

namespace ConsoleApplication4
{   
    abstract class A 
    {
        int i;
        public  abstract void display();
    }    
    class B: A 
    {
        public  int j;
        public override void display() 
        {
            Console.WriteLine(j);
        }
    }    
    class Program
    {
        static void Main(string[] args)
        {
            B obj = new B();
            obj.j = 2;
            obj.display();
            Console.ReadLine();
        }
    }
}