#include <bits/stdc++.h>

using namespace std;

const int maxn = 1000007;
long long phi[maxn];

void sieve() {
    for (int i = 1; i <= maxn; i++) {
        phi[i] = i - 1;
    }

    for (int i = 2; i <= maxn; i++) {
        for (int j = 2*i; j <= maxn; j += i) {
            phi[j] -= phi[i];
        }
    }
}

int main() {
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);

    int n;
    cin >> n;

    sieve();

    long long sol = 0;
    for (int i = 1; i <= n; i++) {
        sol += phi[i] * 2;
    }
    cout << sol + 1 << "\n";

    return 0;
}