import java.util.Scanner;

public class Main {

	public static void main(String args[]){

		Scanner cin = new Scanner(System.in);

		int size = cin.nextInt();
		int hole = cin.nextInt();
                cin.close();
		if(hole == 2*size){
			for(int i=0;i<size;i++){
				System.out.print("B");
			}
		}else{
			for(int j=0;j<size;j++){
				if(hole == 2*(size-j)){
					System.out.print("B");
					hole-=2;
				}else if(hole > 0){
					System.out.print("A");
					hole--;
				}else{
					System.out.print("C");
				}
			}
		}
		System.out.println("");
	}
}