LYNN – The Lynn teen who allegedly snatched $350 from the Lynnfield Street Market on Sunday admitted to police that he gave his girlfriend a chunk of the cash and used the rest to buy marijuana.Matthew David Griggs, 19, of 248 Lynnfield St., was arraigned Monday at Lynn District Court by Judge Albert Conlon, where he was ordered held without bail pending a dangerousness hearing on March 15.According to court documents, Griggs turned himself in to the Lynn police a few hours after the alleged robbery. During an interview, he said he acted alone and stole $350 from the 263 Lynnfield St. market?s cash register. Police say Griggs was armed with a large hunting knife and had a mask partly covering his face at the time of the robbery. Even though his face was covered, the clerk at the store said he immediately recognized the suspect as Griggs, who allegedly comes to the store daily to buy one blunt cigarette.Griggs, who dropped out of school in the ninth grade, told police that he had gotten into a fight with his girlfriend earlier that day about her stealing money and Klonopin pills from her father. Following the robbery, he said he ran to the Lynnfield Street house where he lives with his elderly grandparents and had his girlfriend and two other girls pick him up after he changed his clothes. He also said he had thrown the knife in the snow behind the house, where police later recovered it.Griggs has been charged with armed robbery while masked, assault and battery with a dangerous weapon, knife, and carrying a dangerous weapon, knife.