class Point
{
	def constructor(x, y)
	{
		this.x = x;
		this.y = y;
	}

	def sum()
	{
		return this.x + this.y;
	}
}

class Point3D extends Point 
{
	def constructor(x, y, z) 
	{
		super(x, y);
		this.z = z;
	}

	def sum()
	{
		return super() + this.z;
	}
}

let
point = new Point(10, 20, 30);
point.sum();