#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  ll n;
  cin >> n;
  vector<ll> a(0);
  while (n) {
    a.push_back(n);
    n >>= 1;
  }
  ll sum = accumulate(a.begin(), a.end(), 0LL);
  ll sum2 = sum;
  ll ans = 0;
  while (a.size() > 1) {
    sum2 -= a.back();
    a.pop_back();
    ans = max(ans, sum2 + a.back() - sum);
  }
  cout << ans << endl;
  return 0;
}