#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++)
           for(j=i*2;j<=n;j+=i)
               if(j<=n) v[j]-=v[i];
       v[1]=1;
       /*for (i = 1; i <= n; ++i)
    v[i] = i-1;
for (i = 2; i <= n; ++i)
    for (j = 2*i; j+i <= n; j += i)
        v[j] -= v[i];*/
       for(i=1;i<=n;i++) /*{g<<v[i]<<" ";*/s+=v[i];
       //g<<s<<"\n";
       return s;//g<<s*2-1<<"\n";
   }
   int main(){
       long n;
       f>>n;
       //g<<n;
       //phi(n);
       //g<<"\n";
       g<<phi(n)*2-1<<"\n";
       g.close();
       return 0;
   }