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