About Count the number of strings of length 9 over the alphabet {a, b, c} subject to each of the following restrictions. (a) The first or the last character is a. Solution (b) The string contains at least 8 consecutive a's. Solution (c) The string contains at least 8 consecutive identical characters. Solution (d) The first character is the same as the last character, or the last character is a, or the first character is a. (e) The string contains at least seven consecutive a's. (f)