#include <fstream>

using namespace std;

const char InFile[]="fractii.in";
const char OutFile[]="fractii.out";
const int MaxN=1000005;

ifstream fin(InFile);
ofstream fout(OutFile);
int k[MaxN],n;
unsigned long long rez;

int main()
{
	fin>>n;
	fin.close();
	rez=0;
	for(register int i=1;i<=n;++i)
	{
		k[i]=i-1;
	}
	for(register int i=1;i<=n;++i)
	{
		for(register int j=i*2;j<=n;j+=i)
		{
			k[j]-=k[i];
		}
	}
	for(register int i=1;i<=n;++i)
	{
		rez+=k[i];
	}
	rez=rez*2+1;
	fout<<rez;
	fout.close();
	return 0;
}