A social psychologist was interested in the custom of handshaking. He noticed that some people were more inclined then others to shake hands when they are introduced. One evening when he and his wife had joined hour other couples at a party, he took advantage of the occasion to collect data. He asked each of the other nine people at the party how many people they had shaken hands with during the introductions. He received a different answer, from zero through eight, from each of the nine people. You can assume that husbands and wives don't shake hands with each other during introductions, and of course, people don't shake hands with themselves. Given this information, find out how often the psychologist's wife shook hands.
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