#include <stdio.h>

int a[1000000];

int main()
{
	long n;
	freopen("fractii.in","r",stdin);
	scanf("%ld", &n);
	fclose(stdin);
	
	long long s=0;;
	for (int i=2; i<=n; ++i)
	{
		a[i]=i-1-a[i];
		for (int j=2; i*j <= n; ++j)
			a[i*j]+=a[i];
		s+=a[i];
	}

	freopen ("fractii.out", "w", stdout);
	printf("%lld", 2*s+1);
	fclose(stdout);
	
	return 0;
}