#include <stdio.h>
#include <stdlib.h>
long *p,*s,i,j,n;
double sum=0;

int main(char *argv[],int argc)
{
	FILE *f;
	f=fopen("fractii.in","rt");
	fscanf(f,"%d",&n);
	fclose(f);
	s=(long*)malloc(n*sizeof(long));
    p=(long*)malloc(n*sizeof(long));
	for(i=0;i<=n;i++)
	{
		*(s+i)=0;
		*(p+i)=i;
	}
	if (n==1) sum=1;
	else{
	for(j=2;j<=n;j++)
		if(*(s+j)==0)
		{
			for(i=j;i<=n;i+=j)
			{
				*(s+i)=1;
				*(p+i)=((*(p+i))/j)*(j-1);
			}
		}
	for(i=2;i<=n;i++)
		sum+=(*(p+i));
	sum=sum*2+1;}
	f=fopen("fractii.out","wt");
	fprintf(f,"%.0lf",sum);
	fclose(f);
	return 0;
}