#include <iostream>
#include <utility>

using namespace std;

class Banknote
{
public:
  explicit Banknote(int v) : value{v} { cout << "Raised:" << value << endl; }
  Banknote(Banknote& b) : value(b.value) { b.value = 0; }
  Banknote(Banknote&& b) : value(b.value) { b.value = 0; }
  ~Banknote() { if ( value ) cout << "Lost:" << value << endl; }

  Banknote& operator=(Banknote& b) { std::swap(value, b.value); }
  operator int() const { return value; }
  
private:
  int value;
};

Banknote purchase_goat(Banknote payment)
{
  if ( payment > 100 )
  {
    cout << "Enough money ($" << payment << ") for a goat!" << endl;
    return Banknote{ payment - 100 };
  }
  else
  {
    cout << "Insufficient money ($" << payment << ") for a goat!" << endl;
    return payment;
  }
}

int main()
{
  Banknote a{150}; // Raised $150
  Banknote b{50};  // Raised $50

  {
    Banknote c{ purchase_goat(a) }; // $150 is enough, raises $50 in exchange to "c" and lost $150
    Banknote d{ purchase_goat(c) }; // $50 not enough, $50 exchange transferred to "d"
  } // lost $50 from "d"
  
  Banknote e{ purchase_goat(a) }; // no value left in "a"
  Banknote f{ purchase_goat(b) }; // $50 not enough, $50 exchange transferred to "e"

  return 0; // lost $50 from "f"
}

// Example output (connect to comments above)
//
// Raised:150
// Raised:50
// Enough money ($150) for a goat!
// Raised:50
// Lost:150
// Insufficient money ($50) for a goat!
// Lost:50
// Insufficient money ($0) for a goat!
// Insufficient money ($50) for a goat!
// Lost:50