Police are asking for the public’s help after a man was slashed with a knife while riding an A train in East New York over the weekend. The attack happened Sunday morning around 10:30 a.m. on a northbound A train as it was at the Euclid Avenue station, police said. Investigators say a man approached a 41-year-old rider inside the train car and slashed him on the right shoulder with a knife. Police say the attack happened quickly, and the man ran off and left the station. Emergency crews responded and took the victim to NYC Health + Hospitals/Bellevue. Police say he is expected to be OK. Police have released surveillance video showing the person they are trying to identify. In the video, the man can be seen walking through the train car, wearing a gray hoodie and a black overcoat, and appearing to hold something in his hand. Police say they do not know what led up to the attack and have not said whether the two men knew each other. Anyone who recognizes the man in the video or has information is asked to contact NYPD Crime Stoppers at 1-800-577-TIPS (8477).