import java.io.*;
import java.util.*;
import java.math.BigInteger;

class Main
{
	public static void main(String args[]) throws Exception
	{
		Scanner cin=new Scanner(System.in);
		
		BigInteger bi[] = new BigInteger[251];
		int n, i;
		
		bi[0] = BigInteger.valueOf(1);
		bi[1] = BigInteger.valueOf(1);
		for (i = 2; i < 251; i++)
		{
			bi[i] = bi[i - 2].multiply(BigInteger.valueOf(2)).add(bi[i - 1]);
		}
		while (cin.hasNext())
		{
			n = cin.nextInt();
			System.out.println(bi[n]);
		}
		
	}
}