#include <fstream>

using namespace std;

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

long long n, s, phi[1000001];

int cmmdc(int x, int y)
{
    int r = x%y;

    while(r)
    {
        x = y;
        y = r;
        r= x%y;
    }

    return y;
}

int check2(int x, int y)
{
    if(cmmdc(x,y) != 1)
        return 0;

    return 1;
}

int main()
{
    f>>n;

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

    for (int i = 2; i <= n; ++i)
        for (int j = 2*i; j <= n; j += i)
            phi[j] -= phi[i];

    for(int i=1;i<=n;i++)
        s+=2*phi[i];

    g<<s+1;


    return 0;
}