///////    File Rect.java    ///////

import java.io.*;

class Rect
{
    public static Vector2D getPoint(int i)
          throws IOException
    {   String s;
        float x = 0.0f, y = 0.0f;
        BufferedReader in = new BufferedReader
                 (new InputStreamReader(System.in));
        System.out.print("x"+i+"= "); System.out.flush();
        s = in.readLine();
        x = Float.valueOf(s).floatValue();
        System.out.print("y"+i+"= "); System.out.flush();
        s = in.readLine();   // read keyboard input as string
        y = Float.valueOf(s).floatValue();
        return(new Vector2D(x,y));
    }

    public static void main(String args[])
          throws IOException
    {   int i;
        System.out.println("Enter vertices 0, 1, 2, 3");
        Vector2D[] point = new Vector2D[4];
        for ( i = 0; i < 4; i++)
            point[i] = getPoint(i);
        for ( i = 0; i < 4; i++)
            System.out.print(point[i] + "  ");
        Vector2D v; 
        Vector2D u = point[1].minus(point[0]);
        for ( i = 0; i < 3; i++)
        {  v = point[(i+2)%4].minus(point[i+1]);
           if ( ! u.isPerpendicular(v) )
           {   System.out.println("No, not a rectangle.");
               return;
           }
           u = v;
        }
        System.out.println("Yes, a rectangle.");
    }
}