// This program reads a message and a secret key from the user and
// encrypts the message using a Caesar cipher, shifting each letter.

import java.util.*;

public class SecretMessage {
	public static void main(String[] args) {
		Scanner console = new Scanner(System.in);
		
		System.out.print("Your secret message: ");
		String message = console.nextLine();
		message = message.toLowerCase();
		
		System.out.print("Your secret key: ");
		int key = console.nextInt();
		
		String encoded = encode(message, key);
		System.out.println("The encoded message: " + encoded);
		
		String decoded = encode(encoded, -key);
		System.out.println("The decoded message: " + decoded);
	}
	
	// This method encodes the given text string using a Caesar
	// cipher, shifting each letter by the given number of places.
	public static String encode(String text, int shift) {
		String result = "";
		for (int i = 0; i < text.length(); i++) {
			char letter = text.charAt(i);
			
			// shift only letters (leave other characters alone)
			if (letter >= 'a' && letter <= 'z') {
				letter = (char) (letter + shift);
				
				// may need to wrap around
				if (letter > 'z') {
					letter = (char) (letter - 26);
				} else if (letter < 'a') {
					letter = (char) (letter + 26);
				}
			}
			result += letter;
		}
		return result;
	}
}