#include<fstream>

using namespace std;

int main()
{
    int n,a[100001],i,j,s=0;
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>n;
    for(i=2;i<=n;i++)
    {
        a[i]=i-1;
    }

    for(i=2;i<=n;i++)
    {
        s+=a[i];
        for(j=i+i;j<=n;j+=i)
        {
            a[j]-=a[i];
        }
    }

    g<<2*s+1;
}