fn main() {

    let v1 = input_line_vc::<usize>();
    let mut a = input_line_vc::<i32>();

    a.sort();
    a.reverse();

    let mut result=0;
    for i in 0..v1[1] {
        if a[i] >= 0 {
            result += a[i];
        }
    }

    println!("{}",result);

}

fn input_line_vc<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}