The first line contains three integers $n$, $S$, and $X$ ($2 \leq n \leq 500\,000$, $0 \leq S, X < 2^{30}$, $n$ is \textbf{even}) --- the number of students and the required sum or XOR values in a pair, respectively.

The next line contains $n$ integers $a_1,\ a_2,\ \ldots,\ a_n$ ($0 \leq a_i < 2^{30}$) --- the knowledge levels of the students.