local ior = io.input()
local b, n = ior:read("*n", "*n")
local t = {}
local sum = 0
for i = 1, n do
  local a = ior:read("*n")
  t[i], sum = a, sum + a
end
table.sort(t)
local midpos = math.floor((n + 1) / 2)
local dstval = t[midpos]
if(sum + b < dstval * n) then
  dstval = math.floor((sum + b) / n)
end
local cnt = 0
for i = 1, n do
  cnt = cnt + math.abs(t[i] - dstval)
end
print(cnt)