2 twins are fans of Linkin Park which is for them the best and the only favorite band.
One of them who tells always the truth participated in the fan survey of 2011 whereas the other who lies didn't participate.
For the survey of 2013,both of them participated.Answering the question "how did you get a copy of living things?" they gave different answers,knowing that they have only one copy shared among them.
During the survey examination Linkin Park discovered the liar,so how could they?
indication:don't take in consideration the other fans.