#include <stdio.h>
long a[2000002],n;
int main()
{
   long long s=0;
   long i,j;
   for(i=1; i<=n;++i)
	a[i]=i-1;
   for(i=2;i<=n;++i)
       for(j=2*i;j<=n;j+=i)
		a[j]-=a[i];
   freopen("fractii.in","r",stdin);
   freopen("fractii.out","w",stdout);
   scanf("%d",&n);
   for(i=2;i<=n;i++)
     s= s + a[i];
   printf("%lld",2*s+1);
   return 0;
}