D. Dragon Balls It's an interactive problem. This code can pass, but this one got "Wrong answer on test 14". You can also see these two codes here. I tried test 14 locally. It seems that it can give the right answer. Does anyone know what's wrong with it? By the way, I don't know if I should use something like cout.flush() for interactive problems. It seems that some submissions passed without any cout.flush() or endl. (They simply use "\n" to type a new line.) So should I pay attention to flush my output in such cases?