Write a program WordLadder that takes two 5 -letter strings as command-line arguments, reads in a list of 5-letter words from standard input, and prints a shortest word ladder using the words on standard input connecting the two strings (if it exists). Two words are adjacent in a word ladder chain if they differ in exactly one letter. As an example, the following word ladder connects green and brown:

green greet great groat groan grown brown Write a filter to get the 5-letter words from a system dictionary for standard input or download a list from the booksite. (This game, originally known as doublet, was invented by Lewis Carroll.)