#include <fstream>

using namespace std;

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

int sp[1000004];
long long n,sum=1;

int main()
{
    f >> n;
    for ( int i = 1 ; i <= n ; i ++ )
      sp[i+1]=i;
    for ( int i = 2 ; i <= n ; i ++ )
      {
        sum+=sp[i];
          for ( int j = i+i ; j <= n ; j += i)
           sp[j]=sp[j]-sp[i];
      }

    g << sum*2-1;

    return 0;
}