Double Learn programming Java

import java.util.*;
public class Main
{
	public static void main(String[] args)
	{
		double a, b;
		double area, perimeter, diagonal;

		System.out.print("Enter the width: ");
		a = Double.parseDouble(new Scanner(System.in).nextLine());

		System.out.print("Enter the height: ");
		b = Double.parseDouble(new Scanner(System.in).nextLine());

		perimeter = a * 2 + b * 2;
		System.out.printf("Perimeter: %1$s" + "\r\n", perimeter);

		area = a * b;
		System.out.printf("Area: %1$s" + "\r\n", area);

		diagonal = Math.sqrt(a * a + b * b);
		System.out.printf("Diagonal: %1$s" + "\r\n", diagonal);

	}
}