#!/usr/local/bin/ruby
def age(thisyear, birthyear)
  if thisyear==birthyear
    0
  else
    1+age(thisyear-1, birthyear)
  end
end

STDERR.print "生まれた西暦年は?: "
printf("誕生日後は%d歳ですね\n",
       age(Time.now.year, gets.to_i))