#include <fstream.h>
#define MaxN 1000009

int i,j,n,v[MaxN];
long nr;

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