x = gets
until x.nil?
 sum = []
 num = []
 a = x.to_f
 i = 1
 while i < 11
  if i == 1
   sum << a
   num << a
  elsif i % 2 == 1
    s = num[i-2] / 3
    sum << s
    num << s
  elsif i % 2 == 0
    k = num[i-2] * 2
    sum << k
    num << k
  end
  i += 1
 end

 puts sum.sum
 x = gets
end

