#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>

using namespace std;

// prime before i
int pbi[1000001];

int main()
{
    ifstream in("fractii.in");
    ofstream out("fractii.out");
    
    int n;
    in >> n;
    
    for (int i = 1; i <= n; i++) {
        pbi[i] = i;
    }
    
    for (int  i = 2; i <= n; i++) {
        if (pbi[i] == i) {
            for (int j = i; j <= n; j += i) {
                pbi[j] /= i;
                pbi[j] *= (i - 1);
            }
        }
    }
    
    int nf = 0;
    for (int i = 1; i <= n; i++) {
        nf += pbi[i];
    }
    nf *= 2;
    nf += 1;
    
    out << nf << "\n";
    
    in.close();
    out.close();
    return 0;
}