using System;
using System.Linq;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace MyCompiler {
    class Program {
        public static void Main(string[] args) 
        {
            Console.WriteLine("Hello world!");
            ishex("aacbdb");
            ishex("acabbaa");
            ishex("aacbdbc");
            ishex("abb");
        }
        
        public static void ishex(string str)
        {
            var dic = str.GroupBy(x => x).ToDictionary(x => x.Key,x => x.Count());
            var iseven = (dic.Values.Count(x => x % 2 ==0)) > 0 && dic.Values.Count(x => x ==1) == 1   
                         ? true:false;
            Console.WriteLine(iseven);
        }
    }
}

/*
Create a function that determines whether it is possible to build a palindrome from the characters in a string.

Examples
PossiblePalindrome("acabbaa") ➞ true
// Can make the following palindrome: "aabcbaa"

PossiblePalindrome("aacbdbc") ➞ true
// Can make the following palindrome: "abcdcba"

PossiblePalindrome("aacbdb") ➞ false

PossiblePalindrome("abacbb") ➞ false

*/