28237
 13190
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 8554
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 39004
 22308
 16054
 71468
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 59632
 90783
 5611
 1000
 69475
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 10
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 582
 8
 36961
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 3

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#include <bits/stdc++.h>
namespace cltstream {
char cltin[1048576 + 1], *ih = cltin, *it = cltin;
inline char gc() {
  if (ih == it) {
    it = (ih = cltin) + fread(cltin, 1, 1048576, stdin);
    if (ih == it) return EOF;
  }
  return *ih++;
}
char cltout[1048576 + 1], *oh = cltout, *ot = cltout + 1048576;
inline void pc(char c) {
  if (oh == ot) {
    fwrite(cltout, 1, 1048576, stdout);
    oh = cltout;
  }
  *oh++ = c;
}
template <typename _tp>
inline void read(_tp& x) {
  int sn = 1;
  char c = gc();
  for (; c != 45 && (c < 48 || c > 57) && c != EOF; c = gc())
    ;
  if (c == 45 && c != EOF) sn = -1, c = gc();
  for (x = 0; c >= 48 && c <= 57 && c != EOF;
       x = (x << 3) + (x << 1) + (c ^ 48), c = gc())
    ;
  x *= sn;
}
template <typename _tp>
inline void write(_tp x, char text = -1) {
  if (x < 0) pc(45), x = -x;
  if (!x)
    pc(48);
  else {
    int digit[22];
    for (digit[0] = 0; x; digit[++digit[0]] = x % 10, x /= 10)
      ;
    for (; digit[0]; pc(digit[digit[0]--] ^ 48))
      ;
  }
  if (text >= 0) pc(text);
}
}  // namespace cltstream
int n;
long long ans;
int main() {
  cltstream::read(n);
  for (register int l = 2, r; l <= n; r = n / (n / l),
                    ans += 2LL * (r - l + 1) * (n / l) * (n / l + 1) -
                                      4 * (r - l + 1),
                    l = r + 1)
    ;
  cltstream::write(ans);
  fwrite(cltstream::cltout, 1, cltstream::oh - cltstream::cltout, stdout);
  return 0;
}
