#include<stdio.h>

long long f(int n)
{
	if(n==1)
		return 2;
	return f(n-1)*3+2;
}

int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
		printf("%lld\n",f(n));
	return 0;
}
/**************************************************************
	Problem: 2232
	User: admin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:1144 kb
****************************************************************/