#include <iostream>
#include <fstream >
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int  poz,a,x[1000000],d,minusuri,minusui;
void ciur (int b)
{int i;
    d=1;
    for(i=b+b;i<=a;i+=b)
       {x[i]=d;d++;}
}
int apel (int  c)
{
    if(c==0)return minusui;
    minusui=minusui+c*2;
    apel(c-1);
}
int main()
{ in>>a; int i,ab=0,dd[100];poz=0;
  for(i=2;i<=a/2;i++)
   {ciur(i);if(x[i]==0){x[poz]=i;poz++;if(d-1>=1){dd[ab]=d-1;ab++;}}
          }
     for(i=0;i<ab;i++)
        {minusui=0;
       minusuri=minusuri+apel(dd[i]);
      }
    out<<a*a-minusuri-a+1;
    return 0;
}