N = gets.to_i
A = N.times.map { gets.chomp }
g = 10 ** 10
sum = 0

A.each do |a|
  i, f = a.split('.')
  f = '0' if f.nil?

  v = i.to_i.abs * g + f.ljust(10, '0').to_i

  if a[0] == '-'
    v *= -1
  end

  sum += v
end

l = 10 - sum.abs.to_s.size

if sum == 0
  puts "0.0000000000"
elsif -1.0 * g < sum && sum < 0
  puts "-0." + ('0' * l) + sum.abs.to_s
elsif 0 < sum && sum < g
  puts "0." + ('0' * l) + sum.abs.to_s
else
  puts sum.to_s.insert(-11, '.')
end