#include <algorithm>
#include <fstream>
#include <iostream>
#include <vector>
using namespace std;

const int inf = 0x3f3f3f3f, kMaxN = 1e6 + 5;

#define int64 long long

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int phi[kMaxN];

int main() {
    int n; fin >> n;
    for (int i = 1; i <= n; ++i) {
        phi[i] = i - 1;
    }
    for (int i = 2; i <= n; ++i) {
        for (int j = i * 2; j <= n; j += i) {
            phi[j] -= phi[i];
        }
    }
    int64 sum = 0;
    for (int i = 1; i <= n; ++i) {
        sum += phi[i];
    }
    sum *= 2;
    sum++;

    fout << sum << '\n';
    return 0;
}