#include <fstream>
#define IN_FILE "fractii.in"
#define OUT_FILE "fractii.out"
using namespace std;
fstream fin (IN_FILE, ios::in);
fstream fout (OUT_FILE, ios::out);

int n,rez,x[1000001],i,k;
int main ()
{
    fin>>n;
    for(i=2;i<=n;i++)
      x[i]=i-1;
    for(i=2;i<=n;i++)
    {
       rez+=x[i];
       for(k=2*i;k<=n;k+=i)
          x[k]-=x[i];
    }
    fout<<2*rez+1;
    fin.close();
    fout.close();
    return 0;
}