//nunta   
#include<fstream.h>   
  
int n,k;
long int nr;

void back()
{if(k==n) nr++;
else if(k<n){ k++;back(); k++; back();}

}

int main()
{ifstream f("nunta.in");
ofstream g("nunta.out");
f>>n;
back();

g<<nr;
f.close();   
g.close();   
return 0;   
}