use std::io;

fn main() {
	let mut s1 = String::new();
	io::stdin().read_line(&mut s1).ok();
	let mut nk: Vec<usize> = s1.trim().split_whitespace()
		.map(|e| e.parse().ok().unwrap()).collect();
	let mut s2 = String::new();
	io::stdin().read_line(&mut s2).ok();
	let mut a: Vec<i32> = s2.trim().split_whitespace()
		.map(|e| e.parse().ok().unwrap()).collect();
	a.sort();
	a.reverse();
	let mut ans = 0i32;
	for i in 0..nk[1] {
		if a[i] > 0 { ans += a[i]; }
		if a[i] < 0 {
			ans += a[i];
			break;
		}
	}
	println!("{}", ans);
}