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In processing documents, we often build something called an index, or
an inverted index.  This is simply a set of pairs (WORD, OCCURRENCES)
where WORD is a word occurring in the document, and OCCURRENCES is a
sequence of integers giving the positions (in increasing order) at
which the word occurs.  For example, for a document consisting of the
single sentence "ask not what your country can do for you ask what you
can do for your country", the index will be

ask 0 9

can 5 12

country 4 16

do 6 13

for 7 14

not 1

what 2 10

you 8 11

your 3 15

You are to write a program that reads in a document, then constructs
the index, and then takes a phrase (sequence of words) and uses the
index to decide where (if at all) the phrase appears in the document.
Thus for the above document if you give the phrase "your country" you
should get the output

3 15

The goal of the exercise is to (a) use standard library classes, (b)
write all code exploiting all the information you have, e.g. that
certain sequences are sorted.

You should handle one more complication.  Each word may have a single
terminating comma or semicolon or fullstop.  These should be removed
when making the index.  Also, the first letter maybe capitalized, this
should also be disregarded.  Thus the index should not change if the
input above were given as "Ask not what your country can do for you,
ask what you can do for your country."