Peaceful Negotiation

Long lasting wars bored country A and B, they decided to dispatch n people to have a peaceful negotiation, respectively. The peaceful negotiation will hold on a round table. But the delegate from country A may has conflict with the delegate from country B. Due to this reason, we hope the people who sit in the round table would not have conflict with the people on both sides. To simplify this problem, suppose the delegate from A exactly has one conflict people in the delegate from B, the delegate from B exactly has one conflict people in the delegate from A. Please calculate probability of the seat choice satisfied the request described above.

The input contains several test cases. The first line is a positive integer T which means there are T test cases below. The following T lines each contains a positive integer n(1<=n<=5000) which represents the conflict pairs described above.

The output contains T lines, each represents the probability of the seat choice satisfied the request described above when the n is given. For each test case, output the probability in a single line with the precision to 7 digits after the decimal point.

2
2
3 

0.3333333
0.2666667 

2009 Multi-University Training Contest 15 - Host by BUAA