Write a method that returns the sum of ALL the two block groups of two digits of the input parameter 'a', starting with the right-most block. As preconditions, you may assume that 'a' will be non-negative. The previous sentences are hard to understand unless you see some examples, so here are some examples: If 'a' is 5123 you would return 74. This is because the right-most block of two digits is 23 and the NEXT right-most block of two digits is 51. The sum of 23+51 is 74. If 'a' is 923124 you would return 147. This is because you would add 24+31+92 which equals 147. You have to add ALL the two block groups of digits.