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