require 'date'

s = Date.new(2015, 1, 1)
e = Date.new(2015, 12, 31)

def happy_days(s, e)
  (s..e).count { |d|
    d.month == d.day.to_s.split(//).map(&:to_i).inject(:+)
  }
end

puts happy_days(s, e)