#include <iostream>
#include <fstream>
#include <bitset>

using namespace std;

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

int n;
long long raspuns=1;
int solutie[1000001];

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