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;
int read() {
  int x = 0;
  char c;
  for (c = getchar(); !isdigit(c); c = getchar())
    ;
  for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + (c ^ 48);
  return x;
}
int av[100010];
int vis[100010], prime[100010], cnt;
int es(int n) {
  for (int i = 2; i <= n; ++i) {
    if (!vis[i]) prime[++cnt] = i;
    for (int j = 1; j <= cnt && prime[j] * i <= n; ++j) {
      vis[prime[j] * i] = 1;
      if (!(i % prime[j])) break;
    }
  }
}
int main() {
  int n = read();
  es(n);
  long long ans = 0;
  av[2] = 1;
  for (int i = 1; i <= cnt && prime[i] <= n; ++i) {
    int flag = 0;
    for (int j = 1; prime[i] * j <= n; ++j) {
      if (av[prime[i] * j]) {
        flag = 1;
        break;
      }
    }
    if (flag) {
      for (int j = 2; prime[i] * j <= n; ++j) av[prime[i] * j] = 1, ans += j;
    }
  }
  cout << 4 * ans;
}
