#include<fstream.h>
int main(){
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long int N;
fin>>N;
long int x;
long long nr=N;
for (long i=2;i<=N;i++){
	  x=i;
      if (x%2==0){
	  nr+=N-N/2;
      while (x%2==0)
	     x/=2; }
      for (long int d=3;d<=x;d+=2)
	   if (x%d==0){
	       nr+=N-N/d;
	   while (x%d==0)
	       x/=d;} }
fout<<nr;
fin.close();
fout.close();
return 0;
}