#!/usr/bin/env luajit
require("utils")

local positions = split(io.open(arg[3]):read("*a"), ",")
foreach(positions, tonumber)

local min, max = math.huge, -math.huge
for k, v in pairs(positions) do
	if v < min then min = v end
	if v > max then max = v end
end

function gauss(n)
	return n * (n + 1) / 2
end

local minimum = math.huge
for i = min, max do
	local cost = 0
	for k, v in pairs(positions) do
		cost = cost + gauss(math.abs(i - v))
	end
	if cost < minimum then
		minimum = cost
	end
end

print(minimum)