HackerRank::Algorithms::Strings::Game of Thrones - I

   The only thing which we care about is the number of all the letters from a to z. If the string has an even length then we need to have even number of letters of each type so that we can form a palindrome. If the initial string has an odd length, then we need to have exactly one letter repeating odd number of times and the other letters repeating even number of times.