#include<stdio.h>
#include<math.h> 
long long n;
/*long long euler(long long a)
 {
	long long i,sqr,nr=1,ca;
        ca=a;
        a*=n;
	sqr=(long long)sqrt((double)a);
        a=ca;
	for(i=2;i<=(sqr+1);++i)
	{
		if(a%i)
			nr++;
	}

		return nr;

 }
*/
long long euler(long long a)
 {
	long long nr=1,i;
        for(i=2;i<=n;++i)
	{
        if(a>i)
        {
        if(a%i)
        nr++;
        }
        else
         {
         if(i%a)
         nr++;
         }
	}

		return nr;

 }
int main()
{
	long long sum=0,i;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&n);
	sum=0;
        sum=n;
        for(i=2;i<=n;++i)
	sum+=euler(i);

	printf("%lld",sum);
	return 0;
}