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;
mt19937 rng_32(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 1e5 + 10;
int pre[maxn];
long long sum[maxn];
int f(int x) { return pre[x] = (pre[x] == x ? x : f(pre[x])); }
void in(int x, int y) {
  x = f(x);
  y = f(y);
  pre[x] = y;
}
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) pre[i] = i;
  for (int i = 2; i <= n; i++) {
    for (int j = 2; j * i <= n; j++) {
      in(i, j);
    }
  }
  for (int i = 2; i <= n; i++) {
    int fa = f(i);
    for (int j = 2; j * i <= n; j++) {
      sum[fa] += j * 4ll;
    }
  }
  long long ans = 0;
  for (int i = 1; i <= n; i++) {
    ans = max(ans, sum[i]);
  }
  cout << ans;
  return 0;
}
