import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Scanner;

public class Main53 {
	public static void main(String[] args) {
		Main53 p = new Main53();
	}

	public Main53() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		solve(n);
	}

	public void solve(int n) {
		if(n==0)
			System.out.println(4);
		else{
			double v = 3;
			for(int i=2;i<=n;i++){
				v *= 3.0/4;
			}
			NumberFormat format = DecimalFormat.getInstance();
			format.setMinimumFractionDigits(10);
			System.out.println(format.format(v));
		}
	}

}