SALEM – A Lynn man who admitted to assaulting a 17 year-old with a knife inside an apartment on New Park Street last December may serve up to five years in state prison.Jamal Harrold, 33, last known address of 333 Chatham St., Lynn, pleaded guilty to assault with a dangerous weapon, a knife, and trafficking over 14 grams of cocaine, before Judge David A. Lowy in Salem Superior Court Monday.Harrold was sentenced to 3-5 years in state prison.Once he has completed his sentence, he will be on probation for another two years.The judge agreed to adopt the jointly proposed punishment offered by Assistant District Attorney Kristen R. Buxton and public defense attorney Alice Jayne.Buxton stated she would have produced evidence at trial that last Dec. 22 Harrold showed up unannounced at an unsupervised visit to see his 2-year-old son at 51 New Park St., where he encountered the brother of his child’s mother.When the 17-year-old brother ordered Harrold to leave because he was not supposed to be there, he refused and became angry. The brother grabbed a bat and Harrold pulled out a knife, resulting in a confrontation during which Harrold threatened to stab the 17-year-old.When police later arrested him, they found various quantities of cocaine, along with $4,970 in cash.The judge credited Harrold the 321 days he spent in jail in lieu of bail at the Middleton Jail awaiting trial on his case.