#include <fstream>
#define MAX 1000000
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int n;
int v[MAX];
long long int sol;

int main()
{int i, j ;

    fin >> n;

    for(i=2;i<=n;i++)
        v[i]=i-1;

    v[1] = 1;

    for(i=2;i<=n;i++)
        {sol+=v[i];
        for(j=2*i;j<=n;j+=i)
            v[j]-=v[i];}

    //for(i=1;i<=n;i++)
      //  fout<<v[i]<<' ';
      fout<<sol*2+1;
    return 0;
}