#!/usr/bin/env ruby
#-*- coding: utf-8 -*-

enshuritsu = 0.0
x = 0

while x < 10000000

 y = 4 * x + 1
 
 z = 4 * x + 3
 
 enshuritsu = enshuritsu + (1.0 / y) - (1.0 / z).to_f
 x = x + 1
end

printf("%d回 円周率 %.20f\n",x,enshuritsu * 4.0)