import java.util.*;

public class Main{
        public static void main(String[] args){
                try(Scanner sc = new Scanner(System.in)){
                        int N = sc.nextInt(), D = sc.nextInt();
                        while(N != 0) {
                                 if(D == 0){
                                        System.out.print("C");
                                        N--;
                                 }else if(N * 2 > D){
                                        System.out.print("A");
                                        N--;
                                        D--;
                                } else if(N * 2 == D) {
                                        System.out.print("B");
                                        N--;
                                        D-=2;
                                }
                        }
                        System.out.println("");
                }
        }
}