What city lies on the northern border of the city that administers Changfeng County?
Changfeng County: Changfeng County () is a county in Anhui Province, People's Republic of China, under the administration of Hefei city. Hefei:  Located in the central portion of the province, it borders Huainan to the north, Chuzhou to the northeast, Wuhu to the southeast, Tongling to the south, Anqing to the southwest and Lu'an to the west.
Huainan