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239 Open Math Olympiad
2011 239 Open Mathematical Olympiad
2
2
Part of
2011 239 Open Mathematical Olympiad
Problems
(1)
for each pair 50 people that know one in a pair
Source: 239 2011 J3
5/17/2020
There are
100
100
100
people in the group. Is it possible that for each pair of people exist at least
50
50
50
others, so every in that group knows exactly one person from the pair?
combinatorics