import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int leng = sc.nextInt();
		int hole_num = sc.nextInt();
		
		StringBuilder sb = new StringBuilder();
		if (hole_num==0) {
			for (int i=0; i<leng; i++) {
				sb.append("C");
			}
		}
		else if (hole_num <= leng) {
			for (int i=0; i<leng; i++) {
				if (hole_num > 0) {
					sb.append("A");
					hole_num--;
				}
				else {
					sb.append("C");
				}
			}
		}
		else {
			int b_num = hole_num - leng;
			int a_num = leng - b_num;
			for (int i=0; i<a_num; i++) {
				sb.append("A");
			}
			for (int i=0; i<b_num; i++) {
				sb.append("B");
			}
		}
		System.out.println(sb);
	}
}