fn main() {
    let mut xx = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut xx).ok();
    let mut xx: Vec<i64> = xx.split_whitespace().skip(1).flat_map(str::parse).collect();

    for i in (0..xx.len().saturating_sub(3)).rev() {
        xx[i + 1] += std::mem::replace(&mut xx[i + 3], 0);
    }

    let i = xx.iter().rposition(|&n| n != 0).unwrap_or(0);
    let output: Vec<String> = xx[..=i].iter().map(|&n| n.to_string()).collect();

    println!("{i}");
    println!("{}", output.join(" "));
}