fn g() -> Vec<usize> {
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	s.split_whitespace().flat_map(str::parse).collect()
}
fn main() {
	let (n, mut v) = (g(), g());
	if n[1] < 2 {
		println!("0");
		return;
	}
	v.sort();
	let v: Vec<_> = v.windows(2).map(|a| (a[1] - a[0]).pow(2)).collect();
	let mut a = v[0..n[1] - 1].iter().sum::<usize>();
	(0..=v.len() - n[1]).for_each(|i| {
		a = a.min(a - v[i] + v[i + n[1] - 1]);
	});
	println!("{a}")
}