//horatiu11
# include <cstdio>
# define nmax 1000001
using namespace std;
int n,a[nmax];
long long nr=1;
int main()
{
    int i,j;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;++i)
        a[i]=i-1;
    for(i=2;i<=n;++i)
    {
        for(j=i+i;j<=n;j=j+i)
            a[j]-=a[i];
        nr+=2*a[i];
    }
    printf("%lld\n",nr);
    return 0;
}