#include <fstream.h>
ifstream fin("fractii.in");
ofstream fout("fractii.out");

long S,n;

long euler(long m)
{long double P=m;
long d,w=m;

if (m==1) return 1;

for(d=2;d<=m;d++)
 if(m%d==0)
  {while(m%d==0) m/=d;
   P=P*(d-1)/d;
   }
return (long)P;  
}  


int main()
{long i;
fin>>n; fin.close();
for (i=1;i<=n;i++)
	 S+=euler(i);
fout<<S*2-1;
fout.close();
return 0;
}