//题意自己看，不懂度娘#include <stdio.h>
#include <algorithm>
#include <math.h>
#include <string.h>
using namespace std;
int main(int argc, char *argv[])
{int m; long long int a[10005]={0}; a[0]=0;a[1]=2;long long int gg=0;for(int i=2;i<=36;i++){a[i]=3*a[i-1]+2;//递归公式//printf("%lld\n",a[i]); } while(scanf("%d",&m)!=EOF){ gg=a[m];printf("%lld\n",gg); } return 0;
}//Start-ZJ//2017/12/14/10:40