#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int n,q[1000010],i,j;
long long s;
int main()
{
    f>>n;
    for(i=2;i<=n;++i)
    {
        q[i]+=i-1;
        for (j=2*i;j<=n;j+=i)
        {
            q[j]-=q[i];
        }
        s+=q[i]*2;
    }
    g<<s+1;
    return 0;
}