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

namespace ConsoleApplication4
{   
    abstract class A 
    {
        public int i;
        public abstract void display();
    }    
    class B: A 
    {
        public  int j;
        public int sum;
        public override void display() 
        {
            sum = i + j;
            Console.WriteLine(+i + "\n" + +j);
            Console.WriteLine("sum is:" +sum);
        }
    }    
    class Program
    {
        static void Main(string[] args)
        {
            A obj = new B();
            obj.i = 2;
            B obj1 = new B();
            obj1.j = 10;
            obj.display();
            Console.ReadLine();
        }
    }
}