#include <iostream>
#include <fstream>
using namespace std;
#define Nmax 1000000
std::ifstream fin("fractii.in");
std::ofstream fout("fractii.out");
long long int sol;
int main()
{
    int n, euler[Nmax];
    fin >> n;
    for(int i = 2; i <= n; i++)
        euler[i] = i - 1;
    for(int i = 2; i <= n; i++)
    {
        sol += euler[i];
        for(int j = i * 2; j <=n; j += i)
            euler[j] -= euler[i];

    }
    fout << sol * 2 + 1;
    return 0;
}