#include <fstream>
using namespace std;

int n,
    v[1000001];
long long ct = 0;


int main () {

    ifstream read("fractii.in");
    ofstream write("fractii.out");

    read >> n;

    for(int i = 1; i <= n; i++)
        v[i] = i - 1;

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

    for(int i = 1; i <= n; i++)
        ct += v[i];

    write << 2 * ct + 1;

    return 0;
}