#include <iostream>
using namespace std;
unsigned long long int N,ar[40];
int main()
{
cin>>N;
ar[0]=1;
ar[2]=3;
for(int x=4; x<=N; x+=2)
{
long long int Sum=ar[x-2]*3;
for(int z=4; x-z>=0; z+=2)
{
Sum+=ar[x-z]*2;
}
ar[x]=Sum;
}
cout<<ar[N];
}