<image> A cube's faces are labeled with the numbers 1, 2, 3, 4, 5, and 6. The sum of the numbers on the three faces adjacent to a vertex of the cube is called the "vertex sum" of that vertex. For example, the vertex sum of vertex A in the image is "2 + 5 + 6 = 13". What is the sum of the "vertex sums" of all the vertices of the cube?