#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");

int array[1000005];

int main()
{
    int n;
    f>>n;
    array[1]=0;
    for (int i=2;i<=n;i++)
        array[i]=i-1;

    for (int i=2; i<=n; i++)
        for (int j=2*i; j<=n; j+=i)
            array[j]-=array[i];
    int sum =0;
    for (int i=1; i<=n;i++)
        sum+=array[i];
    g<<2*sum+1;

    return 0;
}