#include<stdio.h>

int n,i,j,v[1000000];
long long nr,p1,p2;

int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);

	scanf("%d",&n);

	for(i=2;i<=n;i++)
	{
		p1=i;
		p2=1;

		for(j=2;j<=i;j++)
			if(!v[j]&&i%j==0)
			{
				p1*=(j-1);
				p2*=j;
			}

		nr+=(p1/p2);

		for(j=2*i;j<=n;j+=i)
			v[j]=1;
	}

	printf("%lld",nr*2+1);

	return 0;
}