I doubt Inflearn's content management ability that allowed this to be sold for 5,500 won. The lecture was not edited at all, to the point where it lasted over an hour for just one problem, and it was a low-difficulty problem, and the solution provided was explained exactly as provided by Google. I never imagined that a problem of this level would be sold for 5,500 won, so it's my fault for paying, but I think this is not the instructor's problem, but Inflearn's problem of not properly reviewing paid content.