import java.io.*;
import java.util.*;


public class Main_yukicoder501 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();
		int d = sc.nextInt();

		int b = Math.max(0, d - n);
		int a = d - 2 * b;
		int c = n - (a + b);

		StringBuilder ret = new StringBuilder();
		while (a-- > 0) {
			ret.append('A');
		}
		while (b-- > 0) {
			ret.append('B');
		}
		while (c-- > 0) {
			ret.append('C');
		}

		pr.println(ret);
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}