Game on Arrays

You are given $4$ arrays of positive integers, namely $A_1$, $A_2$, $A_3$ and $A_4$. Each of them has size $K$, $L$, $M$ and $N$ respectively. You are playing a game which proceeds as follows: - Pick a number each from two different arrays. You delete the entry picked from the respective arrays (i.e. if a number is present multiple times, only delete one of them) and can never use it again. - Mult