ANacci

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


class ANacci
{
    static void Main()
    {
        char firstLetter = char.Parse(Console.ReadLine());
        char secondLetter = char.Parse(Console.ReadLine());

        int l = int.Parse(Console.ReadLine());

        int length = 0;

        for (int i = 1; i < l; i++)
        {
            length += 2;
        }

        length += 1;

        char[] letters = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
                              'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
                               'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};

        char[] m = new char[length];


        if (l == 1)
        {
            m[0] = firstLetter;
            Console.WriteLine(firstLetter);
        }

        if (l >= 2)
        {
            m[0] = firstLetter;
            m[1] = secondLetter;
            Console.WriteLine(firstLetter);
            Console.Write(secondLetter);

            int result = 0;

            for (int i = 2; i < m.Length; i++)
            {
                result = ((m[i - 1] - 'A' + 1) + (m[i - 2] - 'A' + 1));
                if (((m[i - 1] - 'A' + 1) + (m[i - 2] - 'A' + 1)) <= 26)
                {
                    m[i] = letters[result - 1];
                }
                else
                {
                    result = result % 26;
                    m[i] = letters[result - 1];
                }

            }

            Console.Write(m[2]);
            Console.WriteLine();

            int count = 1;

            for (int i = 3; i < m.Length; i++)
            {
                Console.Write(m[i]);

                if (i % 2 == 0)
                {
                    Console.WriteLine();
                    count++;
                }
                else
                {
                    Console.Write(new String(' ', count));
                }
            }
        }
    }
}