// Author   : Apostolos Syropoulos

import java.io.*;

public class hanoiE1
{
  static int moves=0; //number of moves so far
       static int getInt()
       {
           String line;
           BufferedReader in = 
           new BufferedReader(new InputStreamReader(System.in)); 
           try
           {
              line = in.readLine();
              int i = Integer.valueOf(line).intValue();
              return i;
           }
           catch (Exception e)
           {
              System.err.println("***Error: Input is not a number.\n" +
                                 "Input assumed to be the number 1");
              return 1;
           }
       }

       static void hanoi(int   height,
                         int   Pole,
                         int   dir)
       {
           if (height >= 1)
           {
              hanoi(height-1, Pole, Opp(dir)); 
              moveDisk(height, Pole, dir);
              hanoi(height-1, Neigh(Pole, Opp(dir)), Opp(dir));
           }
       }

       static void moveDisk(int disk, int fromPole, int dir)
       {    
            char fromPeg = PoleName(fromPole), 
                 toPeg   = PoleName(Neigh(fromPole, dir));
            
            moves++;
            System.out.print(fromPeg);
            System.out.print(toPeg);
            System.out.print(((moves % 20)==0) ? '\n' : ' ');
       }

       static int Opp(int dir)
       {
	    return (dir == 1) ? 0 : 1;
       }

       static int Neigh(int Pole, int dir)
       {
	    return (Pole + dir) % 3 +1;
       }

       static char PoleName(int pole)
       {
            switch (pole)
	    {
	       case 1: return 'A'; 
	       case 2: return 'B';
	       case 3: return 'C';
	    }
            return 'E';
       }

       public static void main(String[] args)
       {
            long time1, time2; //for benchmarking
            int TowerHeight;
            int FromPole = 1, Dir = 0;

            System.out.println("Enter Tower height...");
            System.out.print("?");
            TowerHeight = getInt();
            time1 = System.currentTimeMillis();
            hanoi(TowerHeight, FromPole, Dir);
            time2 = System.currentTimeMillis();
            System.out.println();
            System.out.print(time2-time1); //print execution time in msec
            System.out.println(" msec execution time");
       }

}