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());
	v.sort();
	let v: Vec<_> = v.windows(2).map(|a| (a[1] - a[0]).pow(2)).collect();
	println!(
		"{}",
		v.windows(n[1] - 1)
			.map(|a| a.iter().sum::<usize>())
			.min()
			.unwrap()
	)
}