Use a stack to reverse the words of a sentence. Keep reading words until you have a word that ends in a period, adding them onto a stack. When you have a word with a period, pop the words off and print them. Stop when there are no more words in the input. For example, you should turn the input Mary had a little lamb. Its fleece was white as snow. into Lamb little a had mary. Snow as white was fleece its. Pay attention to capitalization and the placement of the period.