#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
#define nmax 1000005
int n, s[nmax];
long long suma;
int main()
{
    fin >> n;
    for(int i = 1; i <= n; i++)
    {
        s[i] = i - 1;
        suma += s[i];
    }
    for(int i = 2; i <= n; i++)
        for(int j = i+i; j <= n; j += i)
        {
            s[j] -= s[i];
            suma -= s[i];
        }
    fout << suma * 2 + 1;
}