#include <iostream>
#include <fstream>
using namespace std;

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

int main()
{
    long long nr = 0;
    int n;
    f >> n;

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

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

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

    g << nr*2+1;
}
}