#include <cstdio>

int n;
long long rez;

int a[1<<20];

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    
    scanf("%d", &n);
    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];
    }

    for (int i = 2; i <= n; ++i)
	rez += a[i]*2;
    ++rez;

    printf("%lld", rez);

    return 0;
}