import java.util.Scanner;

public class VigenereCipher {

    public static String encrypt(String text, String key) {
        StringBuilder result = new StringBuilder();
        key = key.toUpperCase();

        int keyIndex = 0;

        for (char ch : text.toCharArray()) {
            if (Character.isLetter(ch)) {
                char base = Character.isUpperCase(ch) ? 'A' : 'a';

                int shift = key.charAt(keyIndex % key.length()) - 'A';

                char encrypted = (char) ((ch - base + shift) % 26 + base);
                result.append(encrypted);

                keyIndex++;
            } else {
                result.append(ch);
            }
        }

        return result.toString();
    }

    public static String decrypt(String text, String key) {
        StringBuilder result = new StringBuilder();
        key = key.toUpperCase();

        int keyIndex = 0;

        for (char ch : text.toCharArray()) {
            if (Character.isLetter(ch)) {
                char base = Character.isUpperCase(ch) ? 'A' : 'a';

                int shift = key.charAt(keyIndex % key.length()) - 'A';

                char decrypted =
                        (char) ((ch - base - shift + 26) % 26 + base);

                result.append(decrypted);
                keyIndex++;
            } else {
                result.append(ch);
            }
        }

        return result.toString();
    }

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

        System.out.print("Enter message: ");
        String message = sc.nextLine();

        System.out.print("Enter key: ");
        String key = sc.nextLine();

        String encrypted = encrypt(message, key);
        String decrypted = decrypt(encrypted, key);

        System.out.println("Encrypted: " + encrypted);
        System.out.println("Decrypted: " + decrypted);

        sc.close();
    }
}