#include <iostream>
#include <ctime>
#include <iomanip>
#include <vector>
#include <map>
#include <algorithm>
#include <string>
#include <cmath>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <chrono>
#include <stack>
#include <cassert>
#include <queue>
#include <deque>
#include <climits>
#include <cstring>
#include <random>
#include <bitset>

using namespace std;

#define int long long

int sum(int n) {
    return (n) * (n + 1) / 2 - 1;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

#ifdef LOCAL
    assert(freopen("input.txt", "r", stdin));
    assert(freopen("output.txt", "w", stdout));
#endif

    int n;
    cin >> n;
    int best = 0;
    for (int i = 2; i < n; i++) {
        int tmp = n / i;
        best += sum(tmp);
    }
    cout << 4 * best;
}