package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	stdin := bufio.NewScanner(os.Stdin)
	stdin.Scan()
	slice := strings.Split(stdin.Text(), " ")
	N, _ := strconv.Atoi(slice[0])
	D, _ := strconv.Atoi(slice[1])

	str := ""
	if D <= 0 {
		for i := 0; i < N; i++ {
			str += "C"
		}
	} else if D <= N {
		for i := 0; i < N; i++ {
			if i < D {
				str += "A"
			} else {
				str += "C"
			}
		}
	} else {
		for i := 0; i < N-(D-N); i++ {
			str += "A"
		}
		for i := 0; i < (D - N); i++ {
			str += "B"
		}
	}
	fmt.Println(str)
}