ぱいおつ

require 'mathn'
require 'benchmark'

puts Benchmark::CAPTION
puts Benchmark.measure{
 n = 1
 tmp0 = 1
 tmp1 = "minus"
 
 150000.times do
  if tmp1 == "minus" then
   n += 2
   tmp0 = tmp0 - (1/n).to_f
   tmp1 = "plus"
  else
   n += 2
   tmp0 = tmp0 + (1/n).to_f
   tmp1 = "minus"
  end
 end
 p 4 * tmp0
}