#include<fstream>
using namespace std;
long v[1000001];
int main()
{
	
	long long i,j,n,nr=0;
ifstream in("fractii.in");
ofstream out("fractii.out");	
in>>n;
	for(i=2;i<=n;i++) v[i]=i-1;
	for(i=2;i<=n;i++)
{
 for(j=i+i;j<=n;j+=i)
	v[j]-=v[i];
nr+=v[i];
}
nr=nr*2+1;
out<<nr;
in.close();
out.close();
return 0;
}