#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    int n, s = 0;
    int prime[1000001];

    f >> n;

    s = n;

    for(int i = 2; i <= n; i++)
        prime[i] = n;

    for(int i = 2; i <= n; i++)
    {
        if(prime[i] == n)
        for(int j = i; j <= n; j += i)
            {
                if(prime[j] == n)
                    prime[j] -= n / i;
                else
                    prime[j] -= n / i - 1;
            }

        s += prime[i];
    }

    cout << s;
}