Problem:
Score : 500 points

Problem Statement

Let N be a positive integer.

There is a numerical sequence of length 3N, a = (a_1, a_2, ..., a_{3N}).
Snuke is constructing a new sequence of length 2N, a', by removing exactly N elements from a without changing the order of the remaining elements.
Here, the score of a' is defined as follows: (the sum of the elements in the first half of a') - (the sum of the elements in the second half of a').

Find the maximum possible score of a'.

Constraints

1 ≤ N ≤ 10^5

a_i is an integer.

1 ≤ a_i ≤ 10^9

Partial Score

In the test set worth 300 points, N ≤ 1000.

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_{3N}

Output

Print the maximum possible score of a'.

Sample Input 1

2
3 1 4 1 5 9

Sample Output 1

1

When a_2 and a_6 are removed, a' will be (3, 4, 1, 5), which has a score of (3 + 4) - (1 + 5) = 1.

Sample Input 2

1
1 2 3

Sample Output 2

-1

For example, when a_1 are removed, a' will be (2, 3), which has a score of 2 - 3 = -1.

Sample Input 3

3
8 2 2 7 4 6 5 3 8

Sample Output 3

5

For example, when a_2, a_3 and a_9 are removed, a' will be (8, 7, 4, 6, 5, 3), which has a score of (8 + 7 + 4) - (6 + 5 + 3) = 5.

Solution in LuaJIT (2.0.4) (judge verdict: Accepted)

local mma = math.max
local mfl, mce, mmi = math.floor, math.ceil, math.min
local SegForAvl = {}
SegForAvl.updateAll = function(self)
  for i = self.stagenum - 1, 1, -1 do
    for j = 1, self.cnt[i] do
      self.stage[i][j] = self.stage[i + 1][j * 2 - 1]
    end
  end
end
SegForAvl.create = function(self, n)
  local stagenum, mul = 1, 1
  self.cnt, self.stage, self.size = {1}, {{}}, {}
  while mul < n do
    mul, stagenum = mul * 2, stagenum + 1
    self.cnt[stagenum], self.stage[stagenum] = mul, {}
  end
  for i = 1, stagenum do self.size[i] = self.cnt[stagenum + 1 - i] end
  self.stagenum = stagenum
  for i = 1, mul do self.stage[stagenum][i] = i end
  self:updateAll()
end
SegForAvl.hold = function(self)
  local idx = self.stage[1][1]
  local ridx = idx
  self.stage[self.stagenum][idx] = false
  for i = self.stagenum - 1, 1, -1 do
    local dst = mce(idx / 2)
    local rem = dst * 4 - 1 - idx
    self.stage[i][dst] = self.stage[i + 1][idx] or self.stage[i + 1][rem]
    idx = dst
  end
  return ridx
end
SegForAvl.release = function(self, idx)
  self.stage[self.stagenum][idx] = idx
  for i = self.stagenum - 1, 1, -1 do
    local dst = mce(idx / 2)
    local rem = dst * 4 - 1 - idx
    self.stage[i][dst] = self.stage[i + 1][idx] or self.stage[i + 1][rem]
    idx = dst
  end
end
SegForAvl.new = function(n)
  local obj = {}
  setmetatable(obj, {__index = SegForAvl})
  obj:create(n)
  return obj
end

local SegAvlTree = {}
SegAvlTree.makenode = function(self, val, parent)
  local i = self.seg:hold()
  self.v[i], self.u[i], self.p[i] = val, true, parent
  self.lc[i], self.rc[i], self.l[i], self.r[i] = 0, 0, 0, 0
  return i
end
SegAvlTree.create = function(self, lessthan, n)
  self.lessthan = lessthan
  self.seg = SegForAvl.new(n)
  -- value, leftCount, rightCount, left, right, parent, used
  self.v, self.lc, self.rc, self.l, self.r, self.p, self.u = {}, {}, {}, {}, {}, {}, {}
  for i = 1, n do
    self.v[i], self.u[i], self.p[i] = 0, false, 0
    self.lc[i], self.rc[i], self.l[i], self.r[i] = 0, 0, 0, 0
  end
end

SegAvlTree.recalcCount = function(self, i)
  if self.u[i] then
    if self.u[self.l[i]] then self.lc[i] = 1 + mma(self.lc[self.l[i]], self.rc[self.l[i]])
    else self.lc[i] = 0
    end
    if self.u[self.r[i]] then self.rc[i] = 1 + mma(self.lc[self.r[i]], self.rc[self.r[i]])
    else self.rc[i] = 0
    end
  end
end
SegAvlTree.recalcCountAll = function(self, i)
  while self.u[i] do
    self:recalcCount(i)
    i = self.p[i]
  end
end

SegAvlTree.rotR = function(self, child, parent)
  local granp = self.p[parent]
  self.r[child], self.l[parent] = parent, self.r[child]
  self.p[child], self.p[parent] = granp, child
  if self.u[self.l[parent]] then self.p[self.l[parent]] = parent end
  if self.u[granp] then
    if self.l[granp] == parent then
      self.l[granp] = child
    else
      self.r[granp] = child
    end
  else
    self.root = child
  end
  self:recalcCountAll(parent)
end

SegAvlTree.rotL = function(self, child, parent)
  local granp = self.p[parent]
  self.l[child], self.r[parent] = parent, self.l[child]
  self.p[child], self.p[parent] = granp, child
  if self.u[self.r[parent]] then self.p[self.r[parent]] = parent end
  if self.u[granp] then
    if self.r[granp] == parent then
      self.r[granp] = child
    else
      self.l[granp] = child
    end
  else
    self.root = child
  end
  self:recalcCountAll(parent)
end

SegAvlTree.add = function(self, val)
  if not self.root then self.root = self:makenode(val, 0) return end
  local pos = self.root
  local added = false
  while not added do
    if self.lessthan(val, self.v[pos]) then
      if self.u[self.l[pos]] then
        pos = self.l[pos]
      else
        self.l[pos] = self:makenode(val, pos)
        pos = self.l[pos]
        added = true
      end
    else
      if self.u[self.r[pos]] then
        pos = self.r[pos]
      else
        self.r[pos] = self:makenode(val, pos)
        pos = self.r[pos]
        added = true
      end
    end
  end
  while self.u[pos] do
    local child, parent = pos, self.p[pos]
    if not self.u[parent] then
      break
    end
    self:recalcCount(parent)
    if self.l[parent] == child then
      if self.lc[parent] - 1 == self.rc[parent] then
        pos = parent
      elseif self.lc[parent] - 2 == self.rc[parent] then
        self:recalcCount(child)
        if self.lc[child] - 1 == self.rc[child] then
          self:rotR(child, parent)
        else
          local cr = self.r[child]
          self:rotL(cr, child)
          self:rotR(cr, parent)
        end
        self:recalcCountAll(child)
        pos = nil
      else
        self:recalcCountAll(child)
        pos = nil
      end
    else -- parent.r == child
      if self.rc[parent] - 1 == self.lc[parent] then
        pos = parent
      elseif self.rc[parent] - 2 == self.lc[parent] then
        self:recalcCount(child)
        if self.rc[child] - 1 == self.lc[child] then
          self:rotL(child, parent)
        else
          local cl = self.l[child]
          self:rotR(cl, child)
          self:rotL(cl, parent)
        end
        self:recalcCountAll(child)
        pos = nil
      else
        self:recalcCountAll(child)
        pos = nil
      end
    end
  end
end

SegAvlTree.rmsub = function(self, node)
  while self.u[node] do
    self:recalcCount(node)
    if self.lc[node] == self.rc[node] then
      node = self.p[node]
    elseif self.lc[node] + 1 == self.rc[node] then
      self:recalcCountAll(self.p[node])
      node = nil
    else
      if self.lc[self.r[node]] == self.rc[self.r[node]] then
        self:rotL(self.r[node], node)
        self:recalcCountAll(node)
        node = nil
      elseif self.lc[self.r[node]] + 1 == self.rc[self.r[node]] then
        local nr = self.r[node]
        self:rotL(nr, node)
        node = nr
      else
        local nrl = self.l[self.r[node]]
        self:rotR(nrl, self.r[node])
        self:rotL(nrl, node)
        node = nrl
      end
    end
  end
end

SegAvlTree.pop = function(self)
  local node = self.root
  while self.u[self.l[node]] do
    node = self.l[node]
  end
  local v = self.v[node]
  if self.u[self.p[node]] then
    if self.u[self.r[node]] then self.p[self.r[node]] = self.p[node] end
    self.l[self.p[node]] = self.r[node]
    self:rmsub(self.p[node])
  else
    if self.r[node] then self.p[self.r[node]] = 0 end
    self.root = self.r[node]
  end
  self.seg:release(node)
  return v
end

SegAvlTree.new = function(lessthan, n)
    local obj = {}
    setmetatable(obj, {__index = SegAvlTree})
    obj:create(lessthan, n)
    return obj
end

local n = io.read("*n", "*l")
local a = {}
local s = io.read()
for str in s:gmatch("%d+") do
  table.insert(a, tonumber(str))
end
local leftsum = {0}
local avleft = SegAvlTree.new(function(x, y) return x < y end, n + 1)
for i = 1, n do
  leftsum[1] = leftsum[1] + a[i]
  avleft:add(a[i])
end
for i = 1, n do
  avleft:add(a[i + n])
  leftsum[i + 1] = leftsum[i] + a[i + n] - avleft:pop()
end
local avright = SegAvlTree.new(function(x, y) return x > y end, n + 1)
local rightsum = {0}
for i = 1, n do
  rightsum[1] = rightsum[1] + a[i + 2 * n]
  avright:add(a[i + 2 * n])
end
for i = 1, n do
  avright:add(a[2 * n + 1 - i])
  rightsum[i + 1] = rightsum[i] + a[2 * n + 1 - i] - avright:pop()
end
local ret = leftsum[1] - rightsum[n + 1]
for i = 2, n + 1 do
  ret = mma(ret, leftsum[i] - rightsum[n + 2 - i])
end
print(ret)