import java.util.*;
import java.io.*;
import java.text.NumberFormat;

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
        float x, y;
        
        NumberFormat nformat = NumberFormat.getInstance(Locale.GERMAN);
        Scanner input = new Scanner(System.in);
        
        System.out.println("Digite o valor de x: ");
        
        try {
        	x = input.nextFloat();
        } catch (InputMismatchException err) {
        	x = nformat.parse(input.nextLine()).floatValue();
        	// err.printStackTrace();
        }
        
        y = (x - ((x* (x - 1)) / (2* x)));
        
        System.out.println("valor calculado por F(x): " + y);
        input.close();
	}
}