#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long long n,i,j, v[10000000],nr;
int main()
{
	fin>>n;
	for(i=1;i<=n;i++)
		v[i]=i-1;
	for(i=2;i<=n;i++)
		{
			j=2*i;
			while(j<=n)
			{
				v[j]-=v[i];
				j+=i;
			}
		}
	for (i=2;i<=n;i++)
		nr+=v[i];
	fout<<nr*2+1<<"\n";
	fin.close();
	fout.close();
	return 0;
}