#include<fstream>
#define inf "fractii.in"
#define outf "fractii.out"
#define NMax 1000010
using namespace std;

fstream f(inf,ios::in),g(outf,ios::out);

int phi[NMax];
int N;

int main()
{
long long int nr=0;
f>>N;
for(int i=1;i<=N;i++)phi[i]=i-1;
for(int i=2;i<=N;i++)
    for(int j=2*i;j<=N;j+=i) phi[j]-=phi[i];
for(int i=2;i<=N;i++)nr+=phi[i];
g<< (2*nr)+1 ;
f.close();
g.close();
return 0;
}