#include<stdio.h>
 
unsigned long long a[999999]; 
  
int main()
{
  unsigned long long i,j,n,nr=0;
   
   
 FILE *f=fopen("fractii.in","r");
 FILE *g=fopen("fractii.out","w");
  
 fscanf(f,"%llu",&n);
  
    for (i=2;i<=n;i++)
        a[i]=i-1;
    for (i=2;i<=n;i++)
        for (j=2*i;j<=n;j=j+i)
            a[j]=a[j]-a[i];
    for (i=2;i<=n;i++)
        nr=nr+a[i]*2;
 fprintf(g,"%llu",nr+1);
}