World's Best Golfer

A pro golfer has the amazing ability to consistently
putt distances of 3, 5, 7, and 11 feet. Strangely
enough, though, those are the only distances he can
putt. Currently, out golfer stands in the green with
his ball 20 feet from he hole. What's the fewest
number of strokes he can use to get the ball into the
hole?

Assume that if the ball is hit farther than the
distance remaining to the hole, it will roll over to
the other side without going into the cup.