#include<fstream>
using namespace std;
int main(){
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	long long n, i, j, s=0, a[1000000];
	scanf("%lld",&n);
	for(i = 1; i <= n; i++)
		a[i] = i;
	
	for(i = 2; i <= n; i++)
	{
		if(a[i]==i)
		{
			
			for(j = i; j <= n; j+=i)
				a[j] = a[j] * (i - 1) / i;
		}
			
	}
	
	for(i = 2; i <= n; i++){
		s+=a[i];
	}
	printf("%lld",(2 * s) + 1);

	
	return 0;
}