题解 | #大吉大利，今晚吃鸡#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            int n = in.nextInt();
            int total = f(n);
            System.out.println(total);
        }
    }
  //手工找到规律——>每个数等于前面的数*3+2
    public static int f(int n) {
        int total = 0;
        for (int i = 0; i < n; i++) {
            total = (total * 3) + 2;
        }
        return total;
    }
}