package com.reno.newwangyi; import java.util.Scanner; public class black { static long summy = 0; public static void same(long deep, long last, long maxdeep) { if (maxdeep == deep) { summy += last; return; } same(deep + 1, last, maxdeep); diff(deep + 1, last * 2, maxdeep); } public static void diff(long deep, long last, long maxdeep) { if (maxdeep == deep) { summy += last; return; } diff(deep + 1, last, maxdeep); same(deep + 1, last, maxdeep); } public static void main(String[] args) { Scanner sc = new Scanner(System.in); while (sc.hasNext()) { summy=0; long n = sc.nextInt(); if (n == 1) { System.out.println(3); continue; } if (n == 2) { System.out.println(9); continue; } same(1, 1, n); long out = 3*summy; System.out.println(out); } } }