#include<fstream.h>
long long a[1000][1000],suma;
int i,j,q,n;
int main()
{
ifstream in("nunta.in");
ofstream out("nunta.out");
in>>n;
for (i=1; i<=n; i++)
		{
		a[i][0]=1;
		a[i][i]=1;
		}
q=n/2;
for (i=2; i<=n-1; i++)
	{
	for (j=1; j<=i-1; j++)
		a[i][j]=a[i-1][j-1]+a[i-1][j];
	if (i>=n-n/2) {suma+=a[i][q];q--;}
	}
out<<suma+1;
in.close();
out.close();
return 0;
}