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;
vector<int> factorize(int n) {
  vector<int> res;
  for (int i = 2; i * i <= n; i++) {
    while (n % i == 0) {
      res.push_back(i);
      n = n / i;
    }
  }
  if (n != 1) res.push_back(n);
  return res;
}
void pack(vector<int> a, int n, vector<pair<int, int> >& v) {
  sort(a.begin(), a.end());
  v.push_back({a[0], 1});
  for (int i = 1; i <= (n - 1); i++) {
    if (a[i] == a[i - 1]) {
      v[(int)(v).size() - 1].second++;
    } else {
      v.push_back({a[i], 1});
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long int n;
  cin >> n;
  long long int cnt = 0;
  for (long long int i = 2; i <= n; i++) {
    for (long long int j = 2 * i; j <= n; j += i) cnt += (j / i);
  }
  cout << (4 * cnt) << '\n';
  return 0;
}
