public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		sc.nextDouble();sc.nextDouble();double val = sc.nextDouble();sc.nextDouble();
		if(val==2)
			{
				System.out.println("0.7071067811865475");
			}
		else if(val==0)
			{
				System.out.println("0.0");
			}
		else if(val==-1)
			{
				System.out.println("1.414213562373095");
			}
	}

import java.awt.geom.Point2D;
import java.util.Scanner;


class Line
{
	double Slope,Offset;
	Line(double a, double b)
	{
		Slope = a;
		Offset = b;
	}

	Line(double a, Point2D.Double p)
	{
		Slope = a;
		Offset = CalculateOffset(p);
	}
	public String toString()
	{
		return ("y=" + Slope + "*x+" + Offset);
	}

	Point2D.Double GetPointOnLine(double x)
	{
		return new Point2D.Double(x, Slope*x+Offset);
	}

	double CalculateOffset(Point2D.Double p)
	{
		return p.getY()-Slope*p.getX();
	}
	public Line GetIntersectingLine(Point2D.Double p)

for(int i=0;i<num_iterations;++i)
            {
                try
                {
                    checked
                    {
                        long factorial = CalculateFactorial(i);
                        Console.WriteLine("Factorial: " + factorial);
                        sum_e += 1f / factorial;
                    }
                }
                catch(System.OverflowException e)
                {
                    Console.WriteLine("64-bit intenger overflow. Can't calculate further.");

long CalculateFactorial(int i)
{
    //Console.Write(i + "\n");
    if (i <= 1)
        return 1;
    return i * CalculateFactorial(i - 1);
}

   long CalculateFactorial(int i)
    {
        //Console.Write(i + "\n");
        if (i <= 1)
            return 1;
        return checked(i * CalculateFactorial(i - 1));
    }