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;
long long int par[100005], sum[100005];
long long int find(long long int x) {
  return (x == par[x] ? x : par[x] = find(par[x]));
}
void uni(long long int x, long long int y) {
  if (x > y) swap(x, y);
  long long int to_add = y / x;
  if ((x = find(x)) != (y = find(y))) {
    par[y] = x;
    sum[x] += sum[y];
    sum[x] += 4ll * (to_add);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  long long int n, i, j, k, x, y, z;
  cin >> n;
  for (i = 1; i <= n; ++i) par[i] = i;
  for (i = 2; i <= n; ++i) {
    for (j = 2; i * j <= n; ++j) {
      uni(i, i * j);
    }
  }
  long long int ans = 0;
  for (i = 1; i <= n; ++i) ans = max(ans, sum[i]);
  cout << ans << endl;
  return 0;
}
