Input: Sentence 1: The stubborn Americans came back again in 1853, with Commodore Matthew Perry bringing for the shogun (whom he mistook for the emperor) a polite but insistent letter from President Millard Fillmore and a promise to return the next year, with a bigger squadron, for a positive response. Sentence 2: The Americans weren't stubborn, knew who the emperor was, and came to peaceful negotiations.
Output: 

 yes