#include<fstream>
#include<cmath>
using namespace std;

const int N = 1000001;
int d[N];

int main()
{
	int n,i,j,s=0;
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	fin>>n;
	for (i=2;i<=n;i++)
		d[i]=i-1;
	for (i=2;i<=n;i++)
	{
		if (d[i]==i-1)
			for (j=2*i;j<=n;j+=i)
				d[j]-=d[i];
		s+=d[i];
	}
	fout<<2*s+1<<'\n';
	fin.close();
	fout.close();
	return 0;
}