How can I prove this?
Suppose X is a set of 16 distinct positive integers, X=\left\{{x_{1}, \cdots , x_{16}}\right\}.
Then, for every X, there exists some integer k\in\left\{{1, \cdots , 8}\right\} and disjoint subsets A,B\subset X
A=\left\{a_{1},\cdots\ ,a_{k}\right\} and...