using System;
using System.Linq;
 
class ABCD
{
    static void Main(string[] args)
    {
        char c = '\0';
        if (args.Length > 1 && args[0] == "-g")
        {
            string gen = String.Join(" ", args.Skip(1));
            for (int i = 0; i < gen.Length; i++)
            {
                if (gen[i] > c)
                    Console.Write(new String('A', (int)(gen[i] - c)));
                else
                    Console.Write(new String('B', (int)(c - gen[i])));
                c = gen[i];
                Console.Write('D');
            }
            return;
        }
        string prog = Console.ReadLine();
        for (int i = 0; i < prog.Length; i++)
            switch (prog[i])
            {
                case 'A':
                    c++;
                    break;
                case 'B':
                    c--;
                    break;
                case 'C':
                    c = (char)Console.Read();
                    break;
                case 'D':
                    Console.Write(c);
                    break;
            }
    }
}

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