import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		new Main().run();
	}

	void run() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int D = sc.nextInt();
		StringBuilder as = new StringBuilder();
		if (D % 2 == 1) {
			as.append("A");
			--D;
			--N;
		}

		// 穴の数D
		// 文字数N

		StringBuilder bs = new StringBuilder();
		StringBuilder cs = new StringBuilder();
		while (N > 0) {
			while (D > N) {
				bs.append("B");
				D -= 2;
				--N;
			}
			while (D > 0) {
				as.append("A");
				--D;
				--N;
			}

			while (N > 0) {
				cs.append("C");
				--N;
			}
		}

		System.out.println(as.append(bs).append(cs));
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}