const C4: f64 = 261.6;
const D4: f64 = 294.3;
const E4: f64 = 327.0;
const F4: f64 = 348.8;
const G4: f64 = 392.4;
const A4: f64 = 436.0;
const B4: f64 = 490.5;

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<isize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let mut sounds = vec![0isize; 7];
    let hz = vec![C4, D4, E4, F4, G4, A4, B4];
    let words = vec!["C4", "D4", "E4", "F4", "G4", "A4", "B4"];
    for j in 0..hz.len() {
        let period = (n as f64 / hz[j]).floor() as usize;
        for i in 0..n/2 {
            sounds[j] += (a[i] - a[i + period]).abs();
        }
    }
eprintln!("{:?}", sounds);
    let idx = sounds.iter().enumerate().min_by_key(|(_, &v)| v).unwrap().0;
    println!("{}", words[idx]);
}