#include<fstream.h>
 ifstream f("fractii.in");
  ofstream g("fractii.out");
   long v[1000001];
   int phi(long n){
       //v[1]=1;
       long long i,j,s=0;
       for(i=1;i<=n;i++) v[i]=i-1;
       for(i=2;i<=n;i++){s+=v[i];
           for(j=i*2;j<=n;j+=i)
               v[j]-=v[i];
       }
       //for(i=1;i<=n;i++) s+=v[i];
       return s;
   }
   int main(){
       long n;
       f>>n;
       g<<phi(n)*2+1<<"\n";
       g.close();
       return 0;
   }