import java.util.*;

import java.math.BigInteger;

public class Main {

	public static void main(String[] args) {

		// TODO Auto-generated method stub

		Scanner sc = new Scanner(System.in);

		BigInteger[] a = new BigInteger[1010];

		a[1] = new BigInteger("0");

		BigInteger one = new BigInteger("1");

		BigInteger two = new BigInteger("2");

		for(int i = 2; i <= 1000; ++i){

			if(i % 2 == 1){

				a[i] = a[i - 1].multiply(two).subtract(one);

			}

			else{

				a[i] = a[i - 1].multiply(two).add(one);

			}

		}

		while(sc.hasNextInt()){

			int n = sc.nextInt();

			System.out.println(a[n]);

		}

	}

}