# include <stdio.h>

FILE *f,*g;

long long s;
long v[1000000],n,i,j;

int main()
{

 f=fopen("fractii.in","r");
 g=fopen("fractii.out","w");

 fscanf(f,"%ld", &n);
 for (i=2;i<=n;i++)
	v[i]=i-1;
 for (i=2;i<=n;i++)
  for (j=2;j<=n/i;j++)
	 v[i*j]-=v[i];
 for (i=2;i<=n;i++)
	 s+=v[i];
 fprintf(g,"%lld",s*2+1);
 fclose(f);
 fclose(g);

 return 0;

}