#include <fstream>

using namespace std;

int N,prim[1000001];
long long s;

int main()
{  ifstream f("fractii.in");
   ofstream g("fractii.out");
   f>>N;
   for (int i = 1; i <= N; ++i)
    prim[i] = i-1;
    for (int i = 2; i <= N; ++i)
    for (int j = 2*i; j <= N; j += i)
                      prim[j] -= prim[i];
		   for(int i=2;i<=N;i++)
		                 s+=prim[i];
		g<<2*s+1;
   return 0;
}