import java.util.Scanner;
import java.text.DecimalFormat;
class CalMath
{
	public static void main(String[] args)
	{
		DecimalFormat f1 = new DecimalFormat("0.0");
		Scanner input = new Scanner(System.in);

		while(input.hasNextDouble())
		{
			double x = input.nextDouble();
			double y = func(x);

			System.out.println(f1.format(y));
		}

		System.out.println("Done.");
	}
	//--------------------------------------
	private static double func(double x)
	{
		double y = Math.sqrt(x+1);
		return y;
	}
}