IL-GILLIS 2020 Problem 2
202 participants arrived at a mathematical conference from three countries: Israel, Greece, and Japan. On the first day of the conference, every pair of participants from the same country shook hands. On the second day, every pair of participants exactly one of whom was Israeli shook hands. On the third day, every pair of participants one of whom was Israeli and the other Greek shook hands. In total 20200 handshakes occurred. How many Israelis participated in the conference?
Dataset text AI-MO AoPS. Quoted with source.
Solutions
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