Yuki is a clever girl and she is a teaching secretary in the department of computer science and engineering (CSE).
There are totally \(n\) students in the department of CSE. One day Yuki is asked to give the full rank list (based on their GPA, where students with the same GPA have the same rank) of these students. However, due to her carelessness, their exact GPA values are missing and only some messages remained. To be specific, there are \(m\) messages remained, each message can be described in one of the following three forms: A<B, A=B or A>B, that is the GPA of student \(A\) is less, equal to or greater than \(B\).
Now Yuki wants to know, based on these \(m\) messages, whether she can obtain the unique full rank list of these students.