$2\mathrm{.}2$ N$-$th Cousin

Write the function nth$\_$cousin$($name$1,$ name$2,$ tree$)$ to find the value n such that name$1$ is the n$-$th cousin of name$2($and vice versa since the relationship is symmetric$).$ If they are not n$-$th cousin, return $-1.$ Remember, the smallest value of n is $1$ if they are cousin.