#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <limits.h>
#include <map>
#include <stack>
#include <algorithm>

using namespace std;

int main()
{
	int n, i;
	cin >> n;

	int a = 2, b = 4, c = 10, temp;

	for (i = 0; i < n-3; i++)
	{
		temp = b;
		b = c;
		c = c * 2 + a * 2;
		a = temp;
	}

	cout << c;
}