#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main()
{int n,i,j,c;
fin>>n;
c=n;
for(i=2;i<=n;i++)
{if(i%2==0){
             if(n%2!=0)c=c+n/2+1;
			 else c=c+n/2;
}
if(i%2!=0)
{
	for(j=1;j<=n;j++)
	{if(j==1)c++;
	if(i%j!=0&&j%i!=0)c++;
	}}}
	fout<<c;
	fin.close();
	fout.close();
	return 0;
}