An 18-year-old girl complains of heaviness and distention in the right hypochondrium. State intensified after eating or taking no-spy. The abdomen is soft, painless, the liver is not enlarged. AsT - 35 OD, AlT - 40 OD. Blood test showed: leukocytes - 5.2 g/l, ESR - 7 mm/h. Ultrasound found: the liver is not enlarged. Gallbladder on an empty stomach 68 ml, after choleretic breakfast for 45 minutes - 64 ml. The wall is not thickened. What is the most likely diagnosis?