import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Yuki053 {
    public static void main(String[] args) {
        Yuki053 hoge = new Yuki053();
    }

    Yuki053() {
        double tmp = 4;

        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();

        for (int i = 0; i < N; i++) {
            tmp = tmp * 3 / 4;
        }
        System.out.println(tmp);
    }

}