https://codeforces.com/contest/264/problem/A

#1


Getting wrong answer in a test case.

#2

From next time, please also post the link to the question in the description itself (makes it easier for us).

It’s okay for now though, I’ll get back to you after seeing your code.

#3

Okay!

Note that it’s not as easy as you think.
The array is of size upto 10^6 and no machine can give you a precision of upto 2^-(10^6) (even in long doubles the precision is only till 10^-15 (approx = 2^(-50)).