#![allow(non_snake_case)]

use std::io::{ self, prelude::* };
use std::process;

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn win_a() -> ! {
    println!("A");
    process::exit(0);
}

fn win_b() -> ! {
    println!("B");
    process::exit(0);
}

fn main() {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    let mut tokens = s.split_whitespace();

    let N: usize    = pick!(tokens);
    let A: Vec<u64> = (0..N).map(|_| pick!(tokens)).collect();

    let s = A.iter().sum::<u64>();
    if s == 0 { win_b(); }
    if s == 1 { win_a(); }
    for i in 0..N {
        if A[i] == 0 { continue; }
        let mut v = A.clone();
        v[i] -= 1;
        let count_one = v.iter().filter(|&&e| e == 1).count() as u64;
        if count_one == s-1 && count_one % 2 == 0 {
            win_a();
        }
    }

    win_b();
}