#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 87;
vector<pair<int, int> > g[N];
bool vis[N];
void add(int a, int b, int w) {
  g[a].emplace_back(b, w);
  g[a].emplace_back(N - b, w);
  g[N - a].emplace_back(b, w);
  g[N - a].emplace_back(N - b, w);
}
long long dfs(int u) {
  long long r = 0;
  vis[u] = 1;
  for (const auto& e : g[u]) {
    r += e.second;
    if (vis[e.first]) continue;
    r += dfs(e.first);
  }
  return r;
}
int main() {
  int n;
  cin >> n;
  for (int i = 2; i <= n; ++i) {
    for (int j = 2; i * j <= n; ++j) {
      int a = i, b = i * j, w = j;
      add(a, b, w);
      add(b, a, w);
    }
  }
  long long ans = 0;
  for (int i = 2; i < N; ++i) {
    if (vis[i]) continue;
    ans = max(ans, dfs(i));
  }
  cout << ans / 2 << endl;
}
