#include <fstream>

using namespace std;

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

int v[1000001];

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