The severely-understaffed NYPD needs your help finding a criminal mastermind who has committed several robberies since May 17 by hailing a cab, getting into it, pulling a gun and demanding money. The most recent of the seven-robbery spree occurred this past Friday night at Delancey and Ludlow Streets in Manhattan. Police say the suspect is about 30 to 40 years old, 6’1” to 6’3” tall, muscular, weighing about 220 to 250 pounds. Intrigued? Get a visual from the New York State Federation of Taxi Drivers, whose members will be at a Midtown taxi stand today to hand out a police sketch of the suspect.