package yukicoder;
import java.util.Scanner;
public class Main{
	public static void main(String[] args)throws Exception{
		new Main().solve();
	}
	void solve(){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		double ans=4;
		for(int i=0;i<n;i++)ans*=(3.0/4.0);
		System.out.println(ans);
	}
}