package no501;

import java.util.Scanner;

public class Main {
	static int[] h = {1,2,0};
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int d = sc.nextInt();
		char[] c = new char[n];
		for(int i=0;i<n;i++) {
			for(int j=0;j<=2;j++) {
				if ((i == n - 1 && d == h[j]) || (i < n - 1 && (n-1-i) * 2 >= d - h[j])) {
					c[i] = (char) ('A' + j);
					d -= h[j];
					break;
				}
			}
		}
		System.out.println(String.valueOf(c));
	}

}