28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

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#include <bits/stdc++.h>
using namespace std;
const int kN = 100000 + 10;
vector<int> g[kN];
bool used[kN];
void Precalc(int n) {
  for (int i = 2; i < n; ++i) {
    for (int j = 2 * i; j < n; j += i) {
      g[i].push_back(j);
      g[j].push_back(i);
    }
  }
}
void Dfs(int u, vector<int>& comp) {
  if (used[u]) {
    return;
  }
  comp.push_back(u);
  used[u] = true;
  for (int v : g[u]) {
    Dfs(v, comp);
  }
}
void Solve() {
  int n;
  cin >> n;
  Precalc(n + 1);
  long long res = 0;
  vector<int> comp;
  for (int u = 2; u <= n; ++u) {
    if (used[u]) {
      continue;
    }
    comp.clear();
    Dfs(u, comp);
    long long curr = 0;
    for (int i : comp) {
      for (int j : g[i]) {
        if (i > j) {
          continue;
        }
        int uu = min(i, j), vv = max(i, j);
        curr += vv / uu;
      }
    }
    res = max(res, curr);
  }
  cout << res * 4 << '\n';
}
int main() {
  std::ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int tests_count = 1;
  for (int test_index = 0; test_index < tests_count; ++test_index) {
    Solve();
  }
  return 0;
}
