After a tough loss, the Bengals traveled further north to take on the Titans.  The Titans drew first blood in the first quarter when DeMarco Murray ran for a 2-yard touchdown to make it 7-0.  The Bengals then got on the board when Andy Dalton found Brandon LaFell on a 37-yard pass (with a failed PAT) to make it 7-6.  The Titans managed to pull away in the second quarter when Murray ran for a 2-yard touchdown to make it 14-6.  The Bengals came within 1 again when Joe Mixon ran for a 3-yard touchdown to make it 14-13.  The Titans then closed out the half with Ryan Succop's 44-yard field goal to make it 17-13 at halftime.  After a scoreless third quarter, the Bengals took the lead in the fourth quarter when Dalton found A.J. Green on a 70-yard pass to make it 20-17.  Though the Titans were able to complete the comeback when Murray ran for his third touchdown of the day:  From 7 yards out to make it 24-20 sealing the win.
Question: How many points were the Titans leading by at halftime?
Answer: 4