N = gets.to_i
C = gets.split.map(&:to_i)
S = C.sum

if S < 0
  N.times do |i|
    C[i] = -1 * C[i]
  end
end

C.sort!
C.reverse!
a = 0
b = 0

C.each_slice(2) do |x, y|
  a += x
  b += y if y
end

puts a.abs - b.abs