context: After a tough loss, the Bengals returned home for a game against the Colts.  The Bengals jumped out to an early lead in the first quarter when Randy Bullock kicked a 29-yard field goal to make it 3-0.  This would be the only score of the quarter.  In the second quarter the Colts scored 10 unanswered points and took the lead when at first they would tie it up with Adam Vinatieri's 29-yard field goal to make it 3-3 followed up by Jacoby Brissett finding Jack Doyle on a 13-yard pass to make it 10-3.  The Bengals tied it up later on in the quarter when Andy Dalton found A.J. Green on an 8-yard pass to make it 10-10.  But the Colts would move ahead at halftime with Vinatieri finishing up with a 33-yard field goal to make it 13-10.  In the third quarter, the Bengals retook the lead 17-13 when Dalton found Josh Malone on a 25-yard pass.  Though the Colts took the lead back afterwards when Brissett found Marlon Mack on a 24-yard pass making it 20-17.  In the fourth quarter, the Colts increased their lead when Vinatieri kicked yet another 29-yard field goal to make it 23-17.  Though the Bengals would eventually seal the victory when Brissett was intercepted by Carlos Dunlap and it was returned for a 16-yard touchdown to make the final score 24-23.
question: How many points did the Colts lead by at halftime?
answer: 3