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