public class Town {
	final int  id;
	final String  name;
	final double  x,y;
	private static final double R= 6378.1370D;
	private static final double CONVERT_DEGREE_TO_RADIANS = Math.PI/180D;
	public Town(int id, String name, double x, double y) {
		this.id = id;
		this.name = name;
		this.x = x*CONVERT_DEGREE_TO_RADIANS;
		this.y = y*CONVERT_DEGREE_TO_RADIANS;
	}
	//distanza dal monumento al monumento inserito

	public double distanceTo(Town b){
		double deltaLat = (b.x - this.x);
		double deltaLon = (b.y-this.y);
		 double a = Math.sin(deltaLat / 2) * Math.sin(deltaLat / 2)
		            + Math.cos(this.x) * Math.cos(b.x)
		            * Math.sin(deltaLon / 2) * Math.sin(deltaLon / 2);
		 double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

		 double distance = R * c * 1000;

		 return Math.sqrt(distance);

	}



}