//nunta
#include<fstream.h>

int s,n,l,p[1000],i;
long int nr;

void back(int k)
{for(int j=p[k-1]+1; j<n;j++)
	{p[k]=j;
	if(p[k]>p[k-1]+1)
		if(k==i) nr++;
		else back(k+1);
	}
}

int main()
{ifstream f("nunta.in");
ofstream g("nunta.out");
f>>n; p[0]=-1;nr=n;
for(i=2;i<=n/2;i++)
	{l=n-i;
	back(1);}
g<<nr;
f.close();
g.close();
return 0;
}