public class Shape {
	
	private Point[] points;
	
	public Shape(int numPoints) {
		this.points = new Point[numPoints];
	}
	
	public void setPoint(int i, Point point) {
		points[i] = point;
	}
	
	public Point getCentreOfMass() {
		double xSum = 0.0;
		double ySum = 0.0;
		double zSum = 0.0;
		
		for (Point point: points) {
			xSum += point.x;
			ySum += point.y;
			zSum += point.z;
		}
		
		return new Point((xSum / points.length), (ySum / points.length), (zSum / points.length));
	}
	
}