Phineas and Ferb Season 1 Episode 43

When Doofenshmirtz's brother Roger is elected mayor, he decides to build his own country, where he can rule over everything, but how will he stop him when Perry is having trouble entering his hideout? Meanwhile, Phineas and Ferb, in an attempt to help Isabella see her "first" rainbow, create the Rainbow-enator, which harnesses the power of their breakfast cereal to make the light show.