func main()
	var n: int :: cui@inputInt()
	var m: int :: cui@inputInt()
	var d: []int :: #[m + 1]int
	for i(0, m - 1)
		do d[i] :: cui@inputInt()
	end for
	do d[m] :: 0
	do d.sort()
	var ans: int :: lib@intMax
	for i(0, m - n)
		var l: int :: d[i].abs()
		var r: int :: d[i + n].abs()
		do ans :: [ans, l + r + [l, r].min()].min()
	end for
	do cui@print("\{ans}\n")
end func