the Cereal Guys friend Serial Guy like watch soap opera an episode start have not wash plate but decide tap fill water the plate represent parallelepipe knm k layer layer upper rectangle nm square obstacle the water present square the tap position square xy layer guarantee square every minute cubical unit water fall plate find minute Serial Guy unglue soap opera turn water overfill plate that find moment time plate absolutely going overfill momentnote water fill area reach sample 4 water flow 6 direction face 111 cube