struct ITarget {};
 
struct ISource {
  virtual ~ISource() {}
};
 
struct IBase {};
 
struct IInput : virtual public IBase, virtual public ITarget {};
 
struct IOutput : virtual public IBase, virtual public ISource {};
 
struct SBase : virtual public IBase, virtual public ISource, virtual public ITarget {};
 
struct SInput : public IInput, public SBase {};
 
struct SOutput : public IOutput, public SBase {};
 
#include <iostream>
 
int main()
{
  ISource* s = new SInput;
  SInput* i = dynamic_cast<SInput*>(s);
  if (i) std::cout << "YES\n";
}
 

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