After their win over the Jets, the Ravens stayed at home for a Week 3 interconference fight with the Arizona Cardinals.  In the first quarter, Baltimore took flight first with kicker Matt Stover getting a 21-yard field goal for the only score of the period.  In the second quarter, the Ravens increased its lead with Stover getting a 28-yard field goal.  The Cardinals would respond with kicker Neil Rackers getting a 48-yard field goal.  Afterwards, Baltimore began to unload with QB Steve McNair completing a 13-yard TD pass to WR Derrick Mason, while rookie WR Yamon Figurs returned a punt 75 yards for a touchdown. In the third quarter, Arizona managed to get a 40-yard field goal from Rackers, while the Ravens had Stover kick a 43-yard field goal.  However, in the fourth quarter, the Cardinals started to work their way back into the game with QB Kurt Warner completing a 5-yard and a 32-yard TD pass to WR Anquan Boldin, along with Rackers getting a 41-yard field goal to tie the game.  Stover helped Baltimore close out the game with a win as he nailed the game-winning 46-yard field goal as time expired.
Question: How many yards was the shortest field goal?
Answer: 21