#include <iostream>
#include <fstream>

using namespace std;
int a[100001], n, s;
int main()
{
    ifstream fin ("fractii.in");
    ofstream fout ("fractii.out");
    fin >> n;

    for(int i = 2; i <= n; i++)
        a[i] = i - 1;

    for(int i = 2; i <= n; i++)
    {
        s += a[i];
        for(int j = i + i; j <= n; j += i)
            a[j] -= a[i];
    }

    fout << s * 2 + 1;
    fin.close();
    fout.close();
    return 0;
}