#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int s[1000004];
int n,suma=1;
int i,j;
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
      s[i+1]=i;
    for(i=2;i<=n;i++)
      {
        suma=suma+s[i];
          for(j=i+i;j<=n;j+=i)
           s[j]=s[j]-s[i];
      }

    g<<suma*2-1;

    return 0;
}