import java.util.ArrayList;

public class NumPad {

public static void main(String[] args) {

String up = "29";

numPad("", up);

System.out.println(numPad("", up));

}

static ArrayList<String> numPad(String p, String up) {

if (up.isEmpty()) {

ArrayList<String> list = new ArrayList<>();

list.add(p);

return list;

}

ArrayList<String> list = new ArrayList<>();

int digit = up.charAt(0) - '0';

for (int i = (digit-2)*3; i <(digit*3)-3 ; i++) {

if (digit == 8 && i == 18 || digit == 9 && i == 21) {

i++;

}

char ch = (char)('a'+i);

list.addAll(numPad(p+ch, up.substring(1)));

if (i == 17 || i == 20 ) {

list.addAll(numPad(p+ (char)(ch+1),up.substring(1) ));

}

if (i == 22 || i == 23 && digit == 9 ) {

list.addAll(numPad(p+ (char)(ch+2),up.substring(1) ));

}

}

return list;

}

}