#include<stdio.h>
#include<iostream.h>
#include<math.h>
long n;
long f(long k)
{
	long ck,i,d=1;
	ck=k-1;
	char v[1000000]={0};
	if(k==2)
		return 1;
	if(!(k%2))
		{
			while(2*d<k)
			{
				v[2*d]=1;
				ck--;
				d++;
			}
		}
	for(i=3;i<sqrt(k);i+=2)
	{
		d=1;
		if(!(k%i))
			while(i*d<k)
			{
				v[2*d]=1;
				ck--;
				d++;
			}
	}
	return ck;
}
int main()
{
	long i;
	long long fract;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	cin>>n;
	for(i=2;i<n;i++)
		fract+=f(i);
	fract*=2;fract++;
	cout<<fract;
	return 0;
}