# coding: utf-8

hole_0 = ("C", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "S", "T", "U", "V", "W", "X", "Y", "Z")
hole_1 = ("A", "D", "O", "P", "Q", "R")
hole_2 = ("B")

# n:文字数 d:穴の数
def read_data():
    N, D = map(int, raw_input().split())
    return N, D

def hole_check(N, D):
    ans = ""
    if N < D:
        n = N
        d = D
        for t in xrange(N):
            if 2*n > d:
                ans += hole_1[0]
            else:
                ans += hole_2[0]
            n -= 1
            d -= 1

    elif N == D:
        for t in xrange(N):
            ans += hole_1[0]
    else:
        for t in xrange(D):
            ans += hole_1[0]
        for t in xrange(N-D):
            ans += hole_0[0]

    print ans

N, D = read_data()
hole_check(N, D)