use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: i32 = itr.next().unwrap().parse().unwrap();
    let d: i32 = itr.next().unwrap().parse().unwrap();

    let mut a = 0i32;
    let mut b = 0i32;
    if d > n {
        b = d - n;
    }
    if d - b * 2 > 0 {
        a = d - b * 2;
    }
    let mut out = Vec::new();
    for _ in 0..a {
        write!(out, "A").ok();
    }
    for _ in 0..b {
        write!(out, "B").ok();
    }
    for _ in 0..n - a - b {
        write!(out, "C").ok();
    }
    stdout().write_all(&out).unwrap();
}