what are the usmc ranks?
['E-1, Private, Pvt.', 'E-2, Private First Class, PFC.', 'E-3, Lance Corporal, LCpl.', 'E-4, Corporal, Cpl.', 'E-5, Sergeant, Sgt.', 'E-6, Staff Sergeant, SSgt.', 'E-7, Gunnery Sergeant, GySgt.', 'E-8. Master Sergeant, MSgt. First Sergeant, 1Sgt.']