IS THERE DIFFERENCE??????
PS.nothing offensive,but if you know why it happened，please telll me.I 've been in codeforces in years,and never seen thing like this.
If you are as.confused as me,then just go.
By the way,I noticed that this question gets some negatives,but with no comment.If you have some idea,just comment it.If not then you are not who I ask help to.Thanks.