#include <fstream>

#define I_F "mushroom.in"
#define O_F "mushroom.out"

const int MAXn=10001+2;

int n;
unsigned long long ans;

void Input();
void Search();
void Output();

int main()
{
	Input();
	Search();
	Output();
	return 0;
}

void Input()
{
	std::ifstream fin(I_F);
	fin>>n;
	fin.close();
}

void Search()
{
	unsigned long long f[2][MAXn]={{0}};
	f[0][2]=1;
	short p=0;
	for (long i=2; i<=n; i++)
	{
		p=1-p;
		for (long j=1+(i%2); j<=i+1; j+=2)
			f[p][j]=f[1-p][j+1]+f[1-p][j-1];
	}
	
	for (long i=1; i<=n+1; ans+=f[p][i++]);
}

void Output()
{
	std::ofstream fout(O_F);
	fout<<ans<<std::endl;
	fout.close();
}