#include<stdio.h>
FILE *f;
int n;
int euler(int k)
{
 int x,d;
 float p=1;
 x=k;
 if(x%2==0)
  p=0.5;
 while(x%2==0)
  x=x/2;
 for(d=3;d<=x;d++)
 {
  if(x%d==0)
   p=p-p/d;
  while(x%d==0)
   x=x/d;
  d++;
 }
  return 2*k*p;
}

void main()
{
 int s=1,l;
 f=fopen("fractii.in","r");
 fscanf(f,"%d",&n);
 fclose(f);
 for (int i=2;i<=n;i++)
 {
  l=euler(i);
  s+=l;
 }
 f=fopen("fractii.out","w");
 fprintf(f,"%d",s);

}