# frozen_string_literal: true

class Array
  def points
    (0..size).map do |n_left|
      s = 0

      each_with_index do |diff, index|
        index < n_left ? (s += diff) : (s -= diff)
      end

      s
    end
  end
end

def solve
  A.each_slice(2)
   .map { |l, r| l - r }
   .points.max
end

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

puts solve