#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream g("fractii.in");
    ofstream f("fractii.out");

   long int n,i,j,s=1,ciur[1000001];
   g>>n;
   for(i=2;i<=n;i++)
    ciur[i]=i-1;
   for(i=2;i<=n;i++)
    for(j=2*i;j<=n;j=j+i)
    ciur[j]=ciur[j]-ciur[i];
   for(i=2;i<=n;i++)
    s=s+2*ciur[i];
   f<<s;
cout<<s;
f.close();
g.close();
}