lib C
  fun strtoll(s : UInt8*, p : UInt8**, b : Int32) : Int64
end

class String
  def to_i64
    C.strtoll(self, nil, 10)
  end
end

def solve(a)
  s = [0i64, 0i64]
  i = 0
  until a.empty?
    s[i % 2] += a.pop
    i += 1
  end
  s[0].abs - s[1].abs
end

n = read_line.to_i
a = read_line.split.map(&.to_i64)
a.map! { |i| -i } if a.sum < 0
a.sort!
puts solve(a)