use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn get_line() -> String {
    let stdin = stdin();
    let mut line = String::new();
    stdin.lock().read_line(&mut line).expect("io error.");
    line.trim().to_string()
}

#[allow(dead_code)]
fn cast<T: FromStr>(s: &str) -> T {
    s.parse().ok().expect("parse error.")
}

#[allow(dead_code)]
fn get_vec<T: FromStr>() -> Vec<T> {
    (&get_line()).split(' ').map(cast::<T>).collect()
}


/* ---------- ここまでテンプレ ---------- */


fn main() {
    let d: usize = cast(&get_line());
    let mut av: Vec<i64> = get_vec();

    if d == 0 {
        println!("0");
        println!("{}", av[0]);
        return;
    }

    for i in (1..d-1).rev() {
        av[i] += av[i + 2];
        av[i + 2] = 0;
    }

    while av.last() == Some(&0) {
        av.pop();
    }
    // println!("{:?}", av);

    if av.is_empty() {av.push(0);};

    println!("{}", av.len() - 1);
    for a in av {
        print!("{} ", a);
    }
    println!("");
}