C++ (NEED ALGORITHM) Counting frequency of words in a Binary Search Tree

How to create a BST where its insert function has two parameters which is key and value. Where these two parameters are templated. So the insert function will be

typename

BST_insert(T key, S value);

Text file is a few dialogues from a play Shakespear Romeo and Juliet (just a scene from it )

Question: how can I get the value to increment? Because in some of the test case the insert key is of type integer and the value is type char. Then there's another case where the inserted key is of type strings, and the value is of type integer. And main question is that I have to check the frequency of the words in a text.file .. So basically, the value will act as a frequency counter in this scenario