#!/usr/bin/env ruby

File.foreach(ARGV[0]) do |l|
  s = []
  l.split.each do |w|
    if w =~ /^[+*\/-]$/
      a,b = s.pop,s.pop
      s.push(b.send(w,a))
    else
      s.push(Float(w))
    end
  end
 
  if s.length == 1 then
     puts s[0]
  else
     $stderr.puts "malformed expression #{l}"
  end
end