Write a c++ program that will read in a line of text and output the number of words in the line and the number of occurrences of each letter. define a word to be any string of letters that is delimited at each end by either whitespace (blank, newline, tab), a period, a comma, or the beginning or end of the line. you can assume that the input consists entirely of letters, whitespace, commas, and periods. when outputting the number of letters that occur in a line, be sure to count upper- and lowercase versions of a letter as the same letter. output the letters in alphabetical order and list only those letters that do occur in the input line.