#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

long long int n,m,i,j,k,sol,x,ans;

int prime[1000001];
int main()
{
    fin >> n;
    for(i = 2;i <= n; ++i)
        prime[i] = i - 1;

    for(i = 2; i <= n; ++i)
    {
        ans += prime[i];
        for(j = i * 2 ; j <= n; j += i)
            prime[j] = prime[j] - prime[i];
    }
  //  for(i = 2;i <= n; ++i)
//      fout << prime[i] <<'\n';
    fout << 2 * ans + 1;
}