a sentence consist lowercase letter z digit 0 9 hyphens punctuation mark space each sentence break tokens separate space a token valid word follow trueIt contain lowercase letter hyphens andor punctuation digitsthere hyphen if present surround lowercase character ab valid ab ab validThere punctuation mark if present end token ab cd valid ab c validexample valid word include ab afad bac give string sentence return number valid word sentence Example 1input sentence cat dogoutput 3explanation the valid word sentence cat dogExample 2input sentence 1s b8doutput 0explanation there valid word sentencethis invalid start punctuation mark1s b8d invalid contain digitsexample 3input sentence alice bob playing stonegame10output 5explanation the valid word sentence alice bob playingstonegame10 invalid contain digits Constraints1 sentencelength 1000sentence contain lowercase english letter digit there 1 token