#include <fstream>

using namespace std;

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

const int Nmax = 1000005;
int v[Nmax];

int main(){
    int n,i,j;
    f >> n;
    for(i = 2 ; i <= n ; i++)
        v[i] = i - 1;

    for(i = 2 ; i <= n / 2 ; i++)
        for(j = 2 * i ; j <= n ; j += i)
            v[j] -= v[i];

    unsigned long long int ans  = 0;
    for(i = 2 ; i <= n ; i++)
        ans += v[i];

    g << ans * 2 + 1;

return 0;
}