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A wizard kidnaps 101 people

Source: Argentina TST 2011, Problem 2

August 29, 2014
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Problem Statement

A wizard kidnaps 3131 members from party AA, 2828 members from party BB, 2323 members from party CC, and 1919 members from party DD, keeping them isolated in individual rooms in his castle, where he forces them to work. Every day, after work, the kidnapped people can walk in the park and talk with each other. However, when three members of three different parties start talking with each other, the wizard reconverts them to the fourth party (there are no conversations with 44 or more people involved).
a) Find out whether it is possible that, after some time, all of the kidnapped people belong to the same party. If the answer is yes, determine to which party they will belong. b) Find all quartets of positive integers that add up to 101101 that if they were to be considered the number of members from the four parties, it is possible that, after some time, all of the kidnapped people belong to the same party, under the same rules imposed by the wizard.