import java.util.*;
public class PrintWords {
	
	static String[] mapping = {"0", "1", "abc", "def", "ghi", "jkl"};
	 
	
	public static void printWords(ArrayList<Integer> nums) {
		printWords(nums, 0, "");
		
	}
	
	public static void printWords(ArrayList<Integer> nums, int position, String prefix) {
		
		//Base case
		if(position == nums.size()-1) {
		
			String currentmapping = mapping[nums.get(position)];
			//System.out.println("position = " + position + " mapping: " + currentmapping);
			for(int i = 0; i < currentmapping.length(); i++) {
				System.out.println(prefix + currentmapping.charAt(i));
			}
			
		} else {
			String currentmapping = mapping[nums.get(position)];
			for(int i = 0; i < currentmapping.length(); i++) {
				printWords(nums, (position+1), (prefix + currentmapping.charAt(i)));
			}
		}
		
	}
	
	public static void main(String[] args) {
	
		ArrayList<Integer> nums = new ArrayList<Integer>();
		nums.add(2);
		nums.add(3);
		nums.add(4);
		//nums.add(5);
		printWords(nums);
		
	}
	
}