When it is 4:00 a.m. in Halifax, it is 1:00 p.m. in Karachi, and when it is 9:00 a.m. in Karachi, it is 5:00 a.m. in Warsaw. Mary left Halifax to fly to Karachi, but she accidentally left her watch on Warsaw time. According to Mary's watch, she left Halifax at 9:40 p.m. on Monday. The local time when she arrived at Karachi was 3:00 p.m. Tuesday. How long was Mary's flight?