# frozen_string_literal: true

class Integer
  def pyramid
    w = 2 * self - 1
    c = self - 1
    a = Array.new(w)
    a[0] = 1
    (1..c).each do |i|
      a[i] = a[i - 1] + 1
    end
    (c + 1..w - 1).each do |i|
      a[i] = a[i - 1] - 1
    end

    a
  end
end

class Array
  def resize(other)
    some = self
    other = other

    if some.size < other.size
      some.fill(some.size, other.size - some.size) { 0 }
    else
      other.fill(other.size, some.size - other.size) { 0 }
    end

    [some, other]
  end
end

def solve
  s = A.sum
  n = Integer.sqrt(s)
  pyramid = n.pyramid
  original, pyramid = A.resize(pyramid)
  original.zip(pyramid).map { |o, p| o - p }.filter { _1 > 0 }.sum
end

N = gets.to_i
A = gets.split.map(&:to_i)

puts solve