C++ Programing Using Strings

Write a 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, a period, a comma, or the beginning 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. For example, the input
line

I say Hi.

Should produce output similar to the following:

3 words

1 a

1 h

2 i

1 s

1 y