#include <fstream>

using namespace std;
ifstream in ("fractii.in");
ofstream out ("fractii.out");
int e[1000001];
int main()
{
    long long s=0;
    int i,j,n;
    in>>n;
    for(i=1;i<=n;i++)
    e[i]=i;
    for(i=2;i<=n;i++)
        if(e[i]==1)//daca e prim
           for(j=1;j<=n;j+=i)
               e[j]=e[j]/i*(i-1);
   for(i=1;i<=n;i++)
   {
       s=s+e[i];
       //out<<i<<"1 "<<"s"<<s<<"ei"<<e[i]<<"\n";
   }
    out<<2*s-1;

    return 0;
}