// A Point object represents a pair of (x, y) coordinates.
// Fourth version: encapsulated, with state, behavior, and constructor.
// Class invariant: x >= 0 && y >= 0 for all Points at all times.

public class Point {
    // fields (the state of each Point object)
    private int x;
    private int y;
    
    // Constructs a new Point object at the origin, (0, 0).
    public Point() {
        setLocation(0, 0);
    }
    
    // Constructs a new Point object with the given initial location.
    public Point(int initialX, int initialY) {
        setLocation(initialX, initialY);
    }
    
    // Returns the distance between this point and the given other point.
    public double distance(Point other) {
        int dx = x - other.x;
        int dy = y - other.y;
        return Math.sqrt(dx * dx + dy * dy);
    }
    
    // Returns the distance between this point and (0, 0).
    public double distanceFromOrigin() {
        return distance(new Point(0, 0));
    }
    
    // Returns this Point's x-coordinate.
    public int getX() {
        return x;
    }
    
    // Returns this Point's y-coordinate.
    public int getY() {
        return y;
    }
    
    // Sets this Point's (x, y) to the given location.
    public void setLocation(int newX, int newY) {
        if (newX < 0 || newY < 0) {
            throw new IllegalArgumentException();
        }
        
        x = newX;
        y = newY;
    }
    
    // Shifts this point's location by the given amounts.
    public void translate(int dx, int dy) {
        setLocation(x + dx, y + dy);
    }
}