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

1028306548 224346172 2054738392 8539207488 94344524 4816051228 5867563092 1962150044 641839188 332342852 6587875268 4721174212 12600 115440 4586497300 10630118936 40580456 1286328 6225539588 6275533596 92 8 434692 52 1762017168 33141852 440 3652070664 11101694484 1065137992 12898363344 10983871880 1856988304 64 8885348 28 0
#include <bits/stdc++.h>
using namespace std;
const int INF = 1 << 29;
inline int two(int n) { return 1 << n; }
long long extgcd(long long a, long long b, long long& x, long long& y) {
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    int g = extgcd(b, a % b, y, x);
    y -= a / b * x;
    return g;
  }
}
long long modpow(long long a, long long b, long long md) {
  long long res = 1;
  a %= md;
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % md;
    a = a * a % md;
  }
  return res;
}
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
const int sz = 1e5 + 5;
bitset<sz> vis;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ifstream in("input.txt");
  ofstream out("output.txt");
  long long n, res = 0;
  cin >> n;
  if (n <= 2) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 2; i < n + 1; i++) {
    if (!vis[i]) {
      vis[i] = 1;
      for (int j = 2 * i; j <= n; j += i) {
        vis[j] = 1;
        res += ((j / i) * 4);
      }
    }
  }
  cout << res << endl;
  return 0;
}
