#include <fstream>

using namespace std;

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

int n, v[10000000], i, j;
long long nr=1;

int main()
{
    in >> n;
    for (i=1; i<=n; i++)
        v[i] = i-1;
    for (i=2; i<=n; i++)
        for (j=2*i; j<=n; j+=i)
            v[j] = v[j]-v[i];
    for(i=1; i<=n; i++)
        nr+=2*v[i];
    out<<nr;
    in.close();
    out.close();
    return 0;
}