Coming off their divisional home win over the Chiefs, the Chargers flew to Heinz Field for a Week 11 duel with the Pittsburgh Steelers.  In the first quarter, the 'Bolts struck first as RB LaDainian Tomlinson got a 3-yard TD run.  In the second quarter, the Steelers slowly responded as LB James Harrison forced a fumble from QB Philip Rivers in his own endzone, which was picked up by OT Marcus McNeill, who got tackled by Harrison in the endzone for a safety.  Pittsburgh would end the half as kicker Jeff Reed got a 21-yard field goal. In the third quarter, the Steelers took the lead as Reed made a 22-yard field goal.  In the fourth quarter, San Diego regained the lead as kicker Nate Kaeding made a 22-yard field goal.  However, Pittsburgh got the lead as Reed nailed a 32-yard field goal. This marked the first time in NFL history that an NFL game ended with a final score of 11-10.
Question: How many yards was Jeff Reed's shortest field goal?
Answer: 21