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

pub fn main() {
    let i = stdin();
    let mut o = Vec::new();
    run(i.lock(), &mut o);
    stdout().write_all(&o).unwrap();
}

fn run<R: BufRead, W: Write>(i: R, o: &mut W) {
    let mut i = CpReader::new(i);
    let d = i.read::<usize>();
    let a = i.read_vec::<i64>(d + 1);
    let r = solve(a);
    writeln!(o, "{}", r.len() - 1).unwrap();
    for i in 0..r.len() {
        if i != 0 {
            write!(o, " ").unwrap();
        }
        write!(o, "{}", r[i]).unwrap();
    }
    writeln!(o, "").unwrap();
}
fn solve(mut a: Vec<i64>) -> Vec<i64> {
    while a.len() >= 4 {
        let i = a.len() - 1;
        a[i - 2] += a[i];
        a.remove(i);
    }
    while a.len() > 1 && a[a.len() - 1] == 0 {
        a.pop();
    }
    a
}

mod utils {
    use super::*;

    pub struct CpReader<R: BufRead> {
        r: R,
        s: String,
    }

    impl<R: BufRead> CpReader<R> {
        pub fn new(r: R) -> Self {
            CpReader {
                r: r,
                s: String::new(),
            }
        }
        pub fn read_line(&mut self) -> &str {
            self.s.clear();
            self.r.read_line(&mut self.s).unwrap();
            self.s.trim()
        }

        pub fn read<T: FromStr>(&mut self) -> T {
            self.read_line().parse().ok().unwrap()
        }
        pub fn read_vec<T: FromStr>(&mut self, n: usize) -> Vec<T> {
            self.read_line()
                .split(' ')
                .take(n)
                .map(|x| x.parse().ok().unwrap())
                .collect()
        }
    }
}