#include <fstream>
#define MAX 1000005

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int phi[1000005];

int main()
{
    int n, sum=0;
    fin >> n;
    for (int i = 1; i <= n; ++i)
        phi[i] = i-1;
    for (int i = 2; i <= n; ++i)
        for (int j = 2*i; j <= n; j += i)
            phi[j] -= phi[i];
    phi[1] = 1;
    for(int i=1; i<=n; i++)
        sum += phi[i];
        //fout << phi[i] << " ";
    fout << 2*sum-1;
    fin.close();
    fout.close();
    return 0;
}