/* Ivan Nicolae - Fractii */
#include <stdio.h>

#define NMAX 1000001
#define _fin  "fractii.in"
#define _fout "fractii.out"

long long n,i,A[NMAX];

int main()
{
 freopen(_fin,"r",stdin);
 freopen(_fout,"w",stdout);

 scanf("%lld",&n);

 for (i=1;i<=n;i++) 
    A[i]=i-1;

 for (i=2;i<=n;i++)
    {
     long long k=2;
     while (k*i<=n)
          {
           A[k*i]-=A[i];
           k++;
          } 
    }

 long long sum=0;
 for (i=1;i<=n;i++)
    sum+=A[i];

 sum*=2; sum++;
 printf("%lld\n",sum);

 fclose(stdin);
 fclose(stdout);
 return 0;
}