#include <iostream>
#include <fstream>
using namespace std;
int v[1000000];
int n;
void ciur()
{

    int i,j;
    v[0]=1;
    v[1]=1;
    for (i=4;i<=n;i=i+2)
        v[i]=1;

        for (i=3;i*i<=n;i=i+2)
           {
               if (v[i]==0)
               for (j=i*i;j<=n;j=j+i*2)
               {
               v[j]=1;
               }
           }
    int aux=0;

    for (i=2;i<=n;i++)
       {
        if (v[i]==0)
        v[++aux]=i;
        }
}
int factori(int x)
{
    int s=1;
    int p=1;
int k;
    int x2=x;
    while (x>1&&v[p]*v[p]<=x)
    {
        if (x%v[p]==0)
        {
           k=1;
            while (x%v[p]==0)
               {
                x=x/v[p];
                k=k*v[p];
               }
                s=s*(k-k/v[p]);
        }
        p++;
    }
    if (x>1)
    {
        s=s*(x-x/x);
    }
    return s;
}
int main()
{
ifstream in("fractii.in");
ofstream out("fractii.out");
in>>n;
ciur();
int i;
int s=0;
for (i=2;i<=n;i++)
{
   s=s+factori(i)*2;
}
out<<s+1;
out.close();
in.close();
return 0;
}