//nunta
#include<fstream.h>

int s,n;
long int nr;

void back(int k)
{ if(s==n) ++nr;
	else if(s<n) {s++; back(k+1);
		s++; back(k+1);
		s-=2;
	}
}

int main()
{ifstream f("nunta.in");
ofstream g("nunta.out");
f>>n;
back(1);
g<<nr;
f.close();
g.close();
return 0;
}