Create DOUBLE.cs

Very easy practice problem from CodeChef. 
http://www.codechef.com/problems/DOUBLE

The program takes in the length of a palindrome "stanleyyelnats"  and returns the maximal number of characters that can be used to form a double string, "stanleystanley".

First line of input is the number of test cases followed by integers.

Input:
2
2
4

Output:
2
4