There are 3 wooden blocks of cubes A, B and C of different sizes. The length of the side of cube A is 1/2 of block B where as the length of side of cube B is 2/3 of cube C. If cubes A, B and C are combined into one big cube with a minimum size (each with at least one cube use done), what is the minimum pieces of the three cubes are needed?

Fig: 1