14 grey cubes and 13 white cubes. 
Jack built a cube using 27 small cubes which are colored either black or white (see figure). No two of the small cubes which are colored in the same color have a common face. How many white cubes did Jack use? 

- $$10$$ 
- $$12$$ 
- $$13$$ 
- $$14$$ 
- $$15$$ 