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

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#include <bits/stdc++.h>
using namespace std;
long long modpow(long long base, long long exp, long long modulus) {
  base %= modulus;
  long long result = 1;
  while (exp > 0) {
    if (exp & 1) result = (result * base) % modulus;
    base = (base * base) % modulus;
    exp >>= 1;
  }
  return result;
}
long long modInverse(long long a, long long m) {
  long long m0 = m;
  long long y = 0, x = 1;
  if (m == 1) return 0;
  while (a > 1) {
    long long q = a / m;
    long long t = m;
    m = a % m, a = t;
    t = y;
    y = x - q * y;
    x = t;
  }
  if (x < 0) x += m0;
  return x;
}
int main() {
  cin.tie(NULL);
  ios_base::sync_with_stdio(false);
  long long n;
  cin >> n;
  if (n == 2) cout << 0;
  if (n == 3) cout << 0;
  long long ans = 0;
  if (n >= 4) {
    for (int(i) = (2); i < (n / 2 + 1); ++(i)) {
      long long num = n / i;
      ans += ((num + 1) * (num)) / 2 - 1;
    }
    cout << ans * 4;
  }
  return 0;
}
