public class Main {
	public static void main(String[] args) throws Exception {
		for (char c = 'A'; c <= 'Z'; c++) {
			System.out.println("A" + c);
			if (c > 'A') {
				System.out.println(c + "" + c);
				for (char c2 = (char) (c - 1); c2 > 'A'; c2--) {
					System.out.println(c + "" + c2);
					System.out.println(c2 + "" + c);
				}
				System.out.println(c + "A");
			}
		}
	}
}