TextParser

A program that counts the number of distinct unique words read from the standard input. For example, given the input "a horse and a dog" the program must output "4" (the word 'a' appears twice but only accounts for one distinct unique occurrence). The input text is guaranteed to contain only 'a'..'z' and space characters in ASCII encoding. The program should use at most 8 GiB RAM. The program should be able to handle at least 32 GiB of input data. The program should be able to give the answer as fast as possible.