bit.cpp

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

signed main() {
  cin.tie(0)->sync_with_stdio(0);
  ll n; cin >> n;
  vector<int> a;
  // chuyen n thanh mang nhi phan
  while (n != 0) {
    a.push_back(n % 2);
    n /= 2;
  }
  ll ans = 0;
  // xet tung vi tri i
  for (int i = 0; i < (int) a.size(); i++) {
    // neu vi tri i la bit 1
    if (a[i] == 1) {
      // truong hop khong thay doi (tuc giu nguyen n) thi co 1 bit
      ans += 1;

      for (int j = 0; j < (int) a.size(); j++) {
        // minh dem so bit 1 o vi tri i nen khong xet truong hop thay doi bit i
        // thay doi bit thu j tu 1 thanh 0 thi moi thay doi cac bit truoc j duoc
        // nen minh bo qua truong hop a[j] == 0
        if (j == i || a[j] == 0) continue;

        // xet truong hop thay doi thay doi bit thu j va j bit dau (0 -> j - 1)
        // neu j > i thi phai tru bot di 1 vi khong thay doi vi tri i
        if (j < i) ans += (1ll << j);
        else ans += (1ll << (j - 1));
      }
    }
    // neu vi tri i la bit 0
    else {
      // minh chi xet nhung vi tri j lon hon i
      // de co the thay doi bit thu i thanh 1
      for (int j = i + 1; j < (int) a.size(); j++) {
        // thay doi bit thu j tu 1 thanh 0 thi moi thay doi cac bit truoc j duoc
        // nen minh bo qua truong hop a[j] == 0
        if (a[j] == 1) {
          // j > i nen phai tru bot di 1 vi khong thay doi vi tri i
          ans += (1ll << (j - 1));
        }
      }
    }
  }
  cout << ans << '\n';
}