#include <stdio.h>

void main()
{
	int n, i;
	long long sum[35] = { 2,8,26 };
	for (i = 3; i < 35; i++)
		sum[i] = 3 * sum[i - 1] + 2;
	while (~scanf_s("%d", &n))
		printf("%lld\n", sum[n - 1]);
}