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;
inline long long gi() {
  long long _x = 0, _tmp = 1;
  char _tc = getchar();
  while ((_tc < '0' || _tc > '9') && _tc != '-') _tc = getchar();
  if (_tc == '-') _tc = getchar(), _tmp = -1;
  while (_tc >= '0' && _tc <= '9') _x *= 10, _x += (_tc - '0'), _tc = getchar();
  return _x * _tmp;
}
void bye() {
  puts("-1");
  exit(0);
}
long long mod7 = 1e9 + 7;
long long inf = INT_MAX - 10;
long long ncase = 1;
long long N, M;
string str;
const int mxn = 3e5 + 5;
void pre() { return; }
void init() { N = gi(); }
void sol() {
  long long res = 0;
  for (int i = 2; i <= N; ++i) {
    for (int j = 2; 1ll * j * i <= N; ++j) {
      res += j * 4;
    }
  }
  cout << res << endl;
  return;
}
int main() {
  pre();
  while (ncase--) {
    init();
    sol();
  }
  return 0;
}
