#include <iostream>
#include <fstream>

using namespace std;

int n;
long long sum;
long long a[1000005];

void initial()
{
    a[1] = 1;
    for(int i = 2; i <= n; i++)
        a[i] = i - 1;
}
void scadere()
{
    for(int i = 2; i <= n; i++)
    {
        sum += a[i];
        for(int j = i + i; j <= n; j += i)
            a[j] -= a[i];
    }
    sum *= 2;
    cout << sum + 1;
}

int main()
{
    cin >> n;
    initial();
    scadere();
}