local n = io.read("*n")
local m = io.read("*n")
local a = {}; do
  for i = 1, n do
    a[i] = io.read("*n")
  end
end

local sum = 0; do
  for i = 1, n do
    sum = sum + a[i]
  end
end

local ans = (function ()
  for i = 1, n - 1 do
    local sub = a[i] - math.floor(sum / (m * n)) * m
    local diff = sub > 0 and sub or 0
    a[i + 1] = a[i + 1] + diff
    a[i] = a[i] - diff
  end
  return math.floor(a[1] / m)
end)()

print(ans)