Direction: 125 cubes of similar size are arranged in the from of a bigger cube (5 cubes on each side, i. e., 5 x 5 x 5). From on corner of the top layer of this cube, four smaller cubes (2 x 2 x 1) are removed. From the column on the opposite side, two cubes (1 x 1 x 2) are removed, and from the third corner,three cubes (1 x 1 x 3) are removed and from the fourth column four cubes (1 x 1 x 4) are removed. All exposed faces of the block thus formed are coloured red.