using System;

public class Program

{

    public static void Main()

    {

        //Console.WriteLine("char code a = " + GetCharacterCode('a'));

        //Console.WriteLine("char code b = " + GetCharacterCode('b'));

        //Console.WriteLine("char code c = " + GetCharacterCode('c'));

        //Console.WriteLine("char code z = " + GetCharacterCode('z'));

        //Console.WriteLine("char code Z = " + GetCharacterCode('Z'));

        //string input = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; // "malayalam" "tushar"

        string input = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; // "malayalam" "tushar"

        int[] arr = BuildCharacterFreqTable(input);

        Console.WriteLine("input: " + input + " | IsPalindrome: " + CheckMaxOneOdd(arr));

    }

    public static bool CheckMaxOneOdd(int[] table)

    {

        bool foundOdd = false;

        foreach (int i in table)

        {

            if (i % 2 == 1)

            {

                if (foundOdd) return false;

                foundOdd = true;

            }

        }

        return foundOdd;

    }

    public static int[] BuildCharacterFreqTable(string str)

    {

        int[] table = new int[520];

        foreach(char c in str)

        {

            int code = GetCharacterCode(c);

            if (c != -1)

                table[code]++;

        }

        return table;

    }

    public static int[] BuildCharacterFreqTable2(string phrase)

    {

        int[] table = new int['z'-'a'+1];

        foreach(char c in phrase.ToCharArray())

        {

            int code = GetCharacterCode(c);

            if (c != -1)

                table[code]++;

        }

        return table;

    }

    public static int GetCharacterCode(char c)

    {

        int a = 'a';

        int z = 'z';

        int val = c;

        if (a <= val && z >= val)

            return val-a;

        return -1;

    }

    public static int GetCharacterCode2(char c)

    {

        /*

        int a = 'a';

        int z = 'z';

        int val = c;

        if (a <= val && z >= val)

            return val-a;

        return -1;

        */

        //Console.WriteLine(c + "= " + (int)c);

        return (int)c;

    }

    static void display(int val = 0)

    {

        Console.Write(val);

    }

}