A maniac pushed a woman onto the subway tracks and punched another lady in the face in Sunset Park, Brooklyn on Saturday — and was later arrested at a nearby shelter, police and sources said. A 51-year-old was shoved and a 43-year-old was socked on the R subway line at 53rd Street and Fourth Avenue around 8:45 a.m., according to cops. A 25-year-old person of interest was taken into custody at the shelter, police sources said, noting both victims suffered facial injuries as well as pain to the legs and back.