A third-generation NYPD cop who graduated from the department’s newest class at Madison Square Garden Monday plans to carry on the “incredible” legacy left by his lineage. “It’s an incredible legacy to carry on with my dad and my grandfather being in the NYPD,” fledgling officer Matthew Vallelong told The Post. “I’m trying to uphold the same values they did their job with, but I also want to try to create my own path within the department and bring my own perspective to the job.” The son of Sergeants Benevolent Association President Vinny Vallelong, the younger Vallelong said hearing the stories from his dad and grandfather, officer Anthony Vallelong, made him want to become a cop “from a very young age.”