#include<cstdio>
#define nmax 1000005

using namespace std;

int tot[nmax],n,i,j,x;
long long s;

int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	
	scanf("%lld",&n);
	
	for(i=2;i<=n;++i)
		tot[i]=i-1;
	for(i=2;i<=n;++i)
	{
		x=i<<2;
		while(x<=n)
		{
			tot[x]-=tot[i];
			x+=i;
		}
		s+=tot[i];
	}
	s=(s<<1)|1;
	
	printf("%lld\n",s);
	
	return 0;
}