package main

import "fmt"

func main() {
	var N, D int

	fmt.Scan(&N, &D)

	// A => 1, B => 2, C => 0
	var aCount, bCount int

	for acnt := 0; acnt <= N; acnt++ {
		bcnt := (D - acnt) / 2

		if bcnt >= 0 && acnt + bcnt * 2 == D && acnt + bcnt <= N {
			aCount = acnt
			bCount = bcnt
		}
	}

	for i := 0; i < aCount; i++ {
		fmt.Print("A")
	}
	for i := 0; i < bCount; i++ {
		fmt.Print("B")
	}
	for i := 0; i < N - (aCount + bCount); i++ {
		fmt.Print("C")
	}
	fmt.Println()
}