#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
#define NMAX 1000010
int main()
{
    int n,euler[NMAX],i,j;
    long long sol=0;
    fin >> n;
    for (i=2;i<=n;i++)
    {
        euler[i]=i-1;
    }
    for (i=2;i<=n;i++)
    {
        sol+=euler[i];
        for (j=2*i;j<=n;j+=i)
        {
            euler[j]-=euler[i];
        }
    }
    fout << 2*sol+1;
    fin.close();
    fout.close();
    return 0;
}