After a tough loss, the Steelers went home to take on the 49ers.  They struck first in the first quarter when Ben Roethlisberger found Heath Miller on a 2-yard TD pass (with a successful 2-point conversion) for an 8-0 lead.  The Niners were able to get on the board in the second quarter when Phil Dawson kicked a 47-yard field goal shortening the lead to 8-3.  The Steelers however pulled away later on as De'Angelo Williams ran for a 2-yard TD (with another successful 2-point conversion) for a 16-3 lead followed up by Roethlisberger finding Darrius Heyward-Bay on a 35-yard TD pass (with a failed PAT) for a 22-3 lead and finally Williams rushing for another 2-yard TD before halftime to take a 29-3 lead.  After a scoreless third quarter, the Niners went to work in the fourth when Colin Kaepernick found Anquan Boldin on a 14-yard TD pass to move behind 29-10.  The Steelers however pulled away when Williams ran for a 1-yard TD to move on up 36-10.  The Niners drew closer when Kaepernick found Torrey Smith on a 75-yard TD pass (with a successful 2-point conversion) to make the score 36-18.  The Steelers however wrapped up the scoring of the game when Roethlisberger found Antonio Brown on a 7-yard TD pass for the final score 43-18. The defense had a field day on Kaepernick by sacking him 5 times and forcing a fumble which they recovered.
Question: How many yards was the longest touchdown pass?
Answer: 75