Read this article and answer this question After a tough win over the Ravens, the Bengals returned home for a game against the Chiefs.  They would score first in the first quarter when Jeremy Hill ran for an 8-yard TD for a 7-0 lead.  Cairo Santos then put a 22-yard field goal through to give the Chiefs their first score of the game 7-3.  The Bengals moved ahead by 11 when Giovani Bernard ran for a 13-yard TD for a 14-3 game.In the second quarter, it was all Chiefs as Santos nailed 3 straight field goals eventually to get within 2 points before halftime:  from 40, 51, and 34 yards out for 14-6, 14-9, and the 14-12 score at halftime.  The Bengals however got back to work in the third quarter when Andy Dalton found Brandon Tate on a 55-yard TD pass increasing their lead to 21-12.  The Chiefs came within 6 as Santos put a 40-yard field goal through for a 21-15 game.  The Bengals moved ahead by 14 when Hill ran for a 5-yard TD (with a successful 2-point conversion) for a 29-15 game.  In the fourth quarter, the Chiefs moved within 11 as Santos put a 29-yard field goal through for a 29-18 game.  The Bengals would pretty much seal the game when Hill ran for a 1-yard TD for a 36-18 game.  The Chiefs wrapped up the scoring of the game when Santos kicked yet another 51-yard field goal for the eventual final score of 36-21. With the win, the Bengals improved to 4-0, their first such start since 2005. The defense also didn't allow a single touchdown (just 7 field goals). They also won their 5th straight home game against the Chiefs.
How many points were the Bengals ahead by at the end of the first half?
2