Coming off an impressive home win over the Patriots, the Broncos flew to Qualcomm Stadium, donned their throwbacks again, and played a Week 6 AFL Legacy game with the San Diego Chargers on Monday night.  Even though the Chargers kicked off the first quarter with a 20-yard field goal from kicker Nate Kaeding, the Broncos immediately struck back with wide receiver Eddie Royal returned the kickoff 93 yards for a touchdown.  San Diego would then close out the opening period with quarterback Philip Rivers hooking up with wide receiver Vincent Jackson on a 3-yard touchdown pass.  Denver would take the lead in the second quarter with kicker Matt Prater making a 34-yard field goal, followed by Royal returning a punt 71 yards for a touchdown.  Afterwards, the Chargers closed out the half with Kaeding nailing a 44-yard field goal and running back Darren Sproles returning a punt 77 yards for a touchdown. Even though San Diego increased their lead in the third quarter with Kaeding's 50-yard field goal, the Broncos regained it with quarterback Kyle Orton completing a 19-yard touchdown pass to tight end Tony Scheffler.  In the fourth quarter, Denver closed out the game with Prater's 29-yard field goal and Orton's 5-yard touchdown pass to wide receiver Brandon Stokley. With the win, the Broncos went into their bye week at 6-0, which is the franchise's best start since their Super Bowl season of 1998.. How many points did the Broncos score on their first drive?