import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        System.out.println("Введте значение N");
        Scanner num_N = new Scanner(System.in);
        int N = num_N.nextInt();
        int Chisl;
        int I ;
        int Znam;
        float Sum ;
        Sum = (1/2);
        Chisl = 1;
        Znam = 2;
        for ( I = 2; I <= N; I++) {
            Znam = Znam * 2;
            Sum = Sum + (Chisl/Znam);
        }
        System.out.printf("Sum = %3f",Sum);
    }
}