#include <fstream>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int i,j,n,a[1000005];
long long s;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
        a[i]=i-1;
    s=1;
    for(i=1;i<=n;i++)
    {
        j=i*2;
        while(j<=n)
        {
            a[j]=a[j]-a[i];
            j+=i;
        }
        s+=2*a[i];
    }
    fout<<s;
    return 0;
}