_ = gets
ary = gets.chomp.split.map(&:to_i)

sum = 0
count = 0
min = Float::INFINITY
ary.each do |i|
    sum += i.abs
    min = i.abs if i.abs < min
    count += 1 if i < 0
end
if count % 2 != 0
    sum -= min * 2
end
puts sum