Twenty.

This is for celesta. This is a transposing instrument, in that the celesta sounds a full octave higher than what is written.

click the image for a clearer view

I've always been a fan of this instrument, though it doesn't always get much use because of its somewhat quiet nature. In an orchestra it can be completely drowned out if the ochestration isn't carefully handled. Give a listen to Holst's The Planets in the movement titled Neptune, the Mystic for a good example of the celesta in a full orchestra, or Bartok's Music for Strings, Percussion and Celesta for its use in a smaller ensemble.