What is the output of following program?

abstract class Sum
{
    public abstract int sumOfTwo(int n1, int n2);
    public abstract int sumOfThree(int n1, int n2, int n3);
    public void disp( ){
        System.out.println("Method of class Sum");
    }
}
class DemoAbstract1 extends Sum
{
    public int sumOfTwo(int num1, int num2)
    {
        return num1+num2;
    }
    public int sumOfThree(int num1, int num2, int num3)
    {
        return num1+num2+num3;
    }
    public static void main(String args[ ]){
        Sum obj = new DemoAbstract1( );
        System.out.println(obj.sumOfTwo(3, 7));
        System.out.println(obj.sumOfThree(4, 3, 19));
        obj.disp( );
    }
}