#!/usr/bin/ruby

require 'pp'

windows = Hash[(1..100).map { | window | [ window, :c ] }]

def switch(windows, window)
  if windows[window] == :c
    windows[window] = :o
  else
    windows[window] = :c
  end
end

(1..100).each do | person |
  #puts "=== person #{person}"
  (0..100).step(person).each do | window |
    next if window == 0
    #puts "window #{window}"
    switch(windows, window)
  end
end

#pp windows
windows.each_pair do | window, state |
  puts window if state == :o
end