interface EqualDiagonal { 
 	public void getDiagonal(); 
  
 } 
  
 class Rectangle implements EqualDiagonal { 
 	int a; 
 	int b; 
  
 	public Rectangle(int a, int b) { 
 		this.a = a; 
 		this.b = b; 
 	} 
  
 	public Rectangle(int a) { 
 		this.a = a; 
 		this.b = a; 
 	} 
  
 	public int getchang() { 
 		return a; 
 	} 
  
 	public int getkuan() { 
 		return b; 
 	} 
  
 	public int getzhouchang() { 
 		return (a + b) * 2; 
 	} 
  
 	public int getmianji() { 
 		return a * b; 
 	} 
  
 	public void getDiagonal() { 
 		double s = Math.sqrt((double) (a * a + b * b)); 
 		System.out.println(s); 
 	} 
  
 } 
  
 class Square extends Rectangle implements EqualDiagonal { 
 	public Square(int a) { 
 		super(a); 
 	} 
  
 	public void getDiagonal() { 
 		double s = Math.sqrt((double) (a * a + b * b)); 
 		System.out.println(s); 
 	} 
 } 
  
 public class Main { 
 	public static void main(String[] args) { 
 		Rectangle m = new Rectangle(3, 4); 
 		Square n = new Square(5); 
 		m.getDiagonal(); 
 		n.getDiagonal(); 
  
 	} 
 } 
  
 //result: 
 //5.0 
 //7.0710678118654755

interface EqualDiagonal
{
    /**
     * 求对角线长度
     */
    public void getDiagonal();

}

/**
 * 长方形
 */
class Rectangle implements EqualDiagonal
{
    int a;
    int b;

    public Rectangle(int a, int b)
    {
        this.a = a;
        this.b = b;
    }

    public int getchang()
    {
        return a;
    }

    public int getkuan()
    {
        return b;
    }

    public int getzhouchang()
    {
        return (a + b) * 2;
    }

    public int getmianji()
    {
        return a * b;
    }

    public void getDiagonal()
    {
        double s = Math.sqrt((double) (a * a + b * b));
        System.out.println(s);
    }

}

/**
 * 正方形
 */
class Square extends Rectangle
{
    public Square(int a)
    {
        super(a, a);
    }

    public void getDiagonal()
    {
        double s = Math.sqrt((double) (a * a + b * b));
        System.out.println(s);
    }
}


public class Text
{
    public static void main(String[] args)
    {
        Rectangle m = new Rectangle(3, 4);
        Square n = new Square(5);
        m.getDiagonal();
        n.getDiagonal();

    }
}