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 8
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#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
inline int pow_(long long a, int n, int p = mod) {
  int r = 1;
  while (n) {
    if (n & 1) r = r * a % p;
    n >>= 1;
    a = a * a % p;
  }
  return r;
}
inline int inv_(int a) { return pow_(a, mod - 2, mod); }
inline int add(int a, int b) {
  a += b;
  if (a >= mod) a -= mod;
  return a;
}
inline void adds(int& a, int b) {
  a += b;
  if (a >= mod) a -= mod;
}
inline int mul(int a, int b) { return a * 1ll * b % mod; }
inline void muls(int& a, int b) { a = a * 1ll * b % mod; }
inline int sub(int a, int b) {
  a -= b;
  if (a < 0) a += mod;
  return a;
}
vector<std::pair<int, int> > g[200100];
bool vis[200100];
long long dfs(int u) {
  vis[u] = true;
  long long ans = 0;
  for (std::pair<int, int> c : g[u]) {
    ans += c.second;
    if (!vis[c.first]) ans += dfs(c.first);
  }
  return ans;
}
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 2; i <= n; ++i) {
    for (int j = i + i; j <= n; j += i) {
      g[i].push_back(make_pair(j, j / i));
      g[j].push_back(make_pair(i, j / i));
    }
  }
  long long f_ans = 0;
  for (int i = 2; i <= n; ++i)
    if (!vis[i]) {
      long long ans = dfs(i);
      f_ans = max(f_ans, ans);
    }
  f_ans *= 2;
  cout << f_ans << "\n";
  return 0;
}
