function GlobalSubtractionHelper(a, b)
{
	return a-b;
}

function Vector2D(x, y)
{
	if (arguments.length == 2)
	{
		this.x = x;
		this.y = y;
	}
	else
	{
		this.x = 0;
		this.y = 0;
	}
}

Vector2D.prototype.add = function(v)
{
	this.x += v.x;
	this.y += v.y;
	return this;
};

function Vector3D(x, y, z)
{
	if (arguments.length == 3)
	{
		this.x = x;
		this.y = y;
		this.z = z;
	}
	else
	{
		this.x = 0;
		this.y = 0;
		this.z = 0;
	}
}
Vector3D.prototype.add = function(v)
{
	this.x += v.x;
	this.y += v.y;
	this.z += v.z;
	return this;
};
