fn main() {
    let mut xx = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut xx).ok();
    let xx: Vec<i64> = xx.split_whitespace().flat_map(str::parse).collect();
    let xx: Vec<Vec<i64>> = xx.chunks(2).map(|x| vec![x[0], -x[1]]).collect();

    let mut abc: Vec<usize> = (0..3).collect();
    abc.sort_unstable_by_key(|&i| &xx[i]);
    abc.reverse();

    for i in abc {
        println!("{}", ['A', 'B', 'C'][i]);
    }
}