#include <fstream>

using namespace std;
ifstream fi("fractii.in");
ofstream fo("fractii.out");
long long n,i,j,s;
int PI[1000001];
int main()
{
    fi >> n;
    for(i = 1; i <= n; i++)
        PI[i] = i - 1;
    PI[1] = 1;
    for(i = 2; i <= n; i++)
        for(j = 2 * i; j <= n; j += i)
            PI[j] -= PI[i];
    for(i = 1; i <= n; i++)
        s += PI[i];
    fo << s * 2 - 1;
    fi.close();
    fo.close();
    return 0;
}