using namespace std;
#include<fstream>
#define NMAX 1000005

ifstream fin("fractii.in");
ofstream fout("fractii.out");

long long S=0;
int N,i,j,tot[1000005];

int main()
{
	fin>>N;

	for(i=2;i<=N;i++)
		tot[i]=i-1;

	for(i=2;i<=N;i++)
	{
		S=S+tot[i];
		for(j=i+i;j<=N;j+=i)
			tot[j]=tot[j]-tot[i];
	}
	
	fout<<2LL*S+1<<"\n";
	return 0;
}