#include <iostream>
#include <cstdio>
using namespace std;

long long rez, n;

bool viz[1000005];

int aranjamente(int aranjamente_de, int luate_cate)
{
    long long fact=1;
    for (int i=luate_cate+1; i<=aranjamente_de; ++i)
    {
        fact*=i;
    }
    return fact;
}

void un_fel_de_ciur(int x)
{
    --rez;
    int aux=x;
    aux+=x;
    int nr=0;
    while (aux<=n)
    {
        viz[aux]=1;
        ++nr;
        rez-=2;
        aux+=x;
    }
    rez-=nr*(nr-1);
    //rez-=(nr+1);
}

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    cin >> n;
    rez=n*n;
    for (int i=2; i<=n; ++i)
    {
        if (!viz[i])
            un_fel_de_ciur(i);
        else
        {
            --rez;
        }
    }
    cout << rez;
    return 0;
}