#include <cstdio>
long long rez;
int N ,i ,j ,cnt[100000];

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

	scanf("%d",&N);
	for(i = 2; i <= N; i++)
	{
		cnt[i] = i-1-cnt[i];
		for(j = 2; j*i <= N; j++)
			cnt[i*j] += cnt[i];
	}

	for(i = 2; i <= N; i++)
		rez += (long long)cnt[i]*2;
	rez++;

		
	printf("%d",rez);
}