class Calc0081
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @n = args.shift.first.to_i
    @as = args.map(&:first)
  end

  def run
    sum = @as.map { |a|
      t = a.split('.')
      t0 = t[0].to_i * 10 ** 10
      t1 = (t[1] || '').ljust(10, '0').to_i * (a.start_with?('-') ? -1 : 1)
      t0 + t1
    }.inject(:+)

    sign = sum >= 0 ? 1 : -1
    "%d.%010d" % [(sum.abs / 10 ** 10) * sign, sum.abs % 10 ** 10]
  end
end

puts Calc0081.new(STDIN.readlines).run if __FILE__ == $0