#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

bool v[1000000];

int main()
{
    int n, r, i, a, j;
    while(fin >> n)
    {
        r = n * n - (n - 1);

        for(i = 2; i<=n; i++)
            v[i] = 0;

        for(i = 2; i <= n; i++)
        {
            a = 0;
            if(v[i] == 0)
                for(j = i + i; j <= n; j+=i)
                {
                    cout << "i = " << i << " | j = " << j << '\n';
                    r -= 2;
                    v[j] = 1;
                    a++;
                }
            if(a > 1)
                r -= a * (a - 1);
        }
        fout << r << '\n';
    }
}