#!/usr/bin/env ruby

require 'optimist'

conf = Optimist::options do
  banner "avg < <one number per line>"
  opt :round, "Number of digits after decimal point.", :type => :int, :default => -1, :short => "-r"
  opt :Running, "Running average", :type => :bool, :default => false, :short => "-R"
end

def print_avg sum, i, round
  avg = sum / i.to_f
  if round >= 0
   puts avg.round round
 else
   puts avg
 end
end

sum = 0.0
i = 0
while line = STDIN.gets
  sum += line.to_f
  i +=1
  if conf[:Running]
    print_avg sum, i.to_f, conf[:round]
  end
end

if not conf[:Running]
  print_avg sum, i.to_f, conf[:round]
end