There are two types of professional wrestlers: "babyfaces" $("$good guys"$)$ and "heels" $("$bad guys"$).$ Between any pair of professional wrestlers, there may or may not be a rivalry. Suppose we have n professional wrestlers and we have a list of r pairs of wrestlers for which there are rivalries. Give an O$($n$+$r$)$ time algorithm that determines whether it is possible to designate some of the wrestlers as babyfaces and the remainder as heels such that each rivalry is between a babyface and a heel. If it is possible to perform such a designation, your algorithm should produce it$.$

Write a proper psueodocode for this problem.