In this problem, we will consider 13-digit numbers in thirteen-decimal notation (digits 0,1,2,3,4,5,6,7,8,9, A, B, C) with leading zeros. For example, ABA98859978C0, 6789110551234, 0000007000000 Let's call a number "beautiful" if the sum of its first six digits is equal to the sum of the last six digits Example: The number 0055237050A00 is "beautiful", since 0 + 0 + 5 + 5 + 2 + 3 = 0 + 5 + 0 + A + 0 + 0 The number 1234AB988BABA is "ugly", since 1 + 2 + 3 + 4 + A + B! = 8 + 8 + B + A + B + A Get the number of "pretty" numbers. Describe the solution process