SALEM – A man who police say they caught trying to enter through the roof of an Essex Street market in Lynn last fall is headed to prison for 30 months.Thomas Nee, 39, of 22 Summer St., Dedham, changed his plea to guilty Wednesday in Salem Superior Court to charges of attempting to commit a crime as well as destruction of property over $250.He was sentenced to serve 30 months in state prison by Judge Timothy Q. Feeley.The judge adopted the joint sentence proposed by the prosecutor and defense.The charges arise from an incident last Oct. 22 when police responded to a call of a man on the roof of the Lincoln Market at 200 Essex St.Police found Nee on the roof of the market and arrested him.Police said there was damage to the A/C ventilation shaft. The business owner acknowledged that the air conditioning shaft had been used in the past to rob the store.The sentence imposed will wipe out the penalty Nee is currently serving on an unrelated crime.The judge agreed to credit Nee the 155 days he has spent in jail awaiting trial on the case.Assistant District Attorney A.J. Camelio prosecuted the case and Rebecca E. Whitehill was the defense attorney.