import java.util.*;
import java.lang.*;
import java.io.*;
 
class Ideone
{
	public static void main (String[] args) {
		char[] letters = "abcdef".toCharArray();
		char[] sequence = "00000".toCharArray();
 
		for (char letter : letters) {
		  moveRight(sequence, letter);
		  System.out.println(sequence);
		}
	}
 
	public static void moveRight(char[] sequence, char letterToAdd) {
	  moveRight(sequence, sequence.length - 1);
	  sequence[0] = letterToAdd;
	}
 
	private static void moveRight(char[] sequence, int lastIndex) {
	  if (1 > lastIndex) {
	    return;
	  }
 
	  sequence[lastIndex] = sequence[lastIndex - 1];
	  moveRight(sequence, lastIndex - 1);
	}
}

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