import java.util.Scanner;
import java.util.*;

public class Encryptor
{
	private final static int NUM_LETTERS = 25;
	private char[] abc = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
	public String encrypt(int key, String msg){
		msg = msg.toLowerCase();
		char[] charMsg = msg.toCharArray();
		ArrayList<Character> newMsg = new ArrayList<Character>();
		for(int i=0; i<charMsg.length; i++){
			if(charMsg[i] == ' '){
				newMsg.add(' ');
			}
			for(int x = 0; x < this.abc.length; x++){
				if(charMsg[i] == this.abc[x]){
					if(x + key > NUM_LETTERS){
						int diff = x+key-NUM_LETTERS;
						x = diff-4;
					}
					newMsg.add(this.abc[x+key]);
					break;
				}
			}
		}

		StringBuilder builder = new StringBuilder(newMsg.size());
	    for(Character ch: newMsg)
	    {
	        builder.append(ch);
	    }
	    return builder.toString();

	}

	public String decrypt(int key, String msg){
		char[] charMsg = msg.toCharArray();
		ArrayList<Character> newMsg = new ArrayList<Character>();
		for(int i=0; i<charMsg.length; i++){
			if(charMsg[i] == ' '){
				newMsg.add(' ');
			}
			for(int x = 0; x < this.abc.length; x++){
				if(charMsg[i] == this.abc[x]){
					if(x - key < 0){
						x = NUM_LETTERS+(x-key+1);

						newMsg.add(this.abc[x]);
						break;
					}

					newMsg.add(this.abc[x-key]);
					break;
				}
			}
		}

		StringBuilder builder = new StringBuilder(newMsg.size());
	    for(Character ch: newMsg)
	    {
	        builder.append(ch);
	    }
	    return builder.toString();
	}

	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);

		Encryptor e = new Encryptor();
		System.out.println("Enter your message");
		String encryptedMsg = e.encrypt(3, scan.nextLine());
		System.out.println(encryptedMsg);
		System.out.println(e.decrypt(3, encryptedMsg));




	}
}