Comparing two arrays & get the values which are not common

i wanted a small logic to compare contents of two arrays & get the value which is not common amongst them using powershell example if ``` $a1=@(1,2,3,4,5) $b1=@(1,2,3,4,5,6) ``` $c which is the output should give me the value "`6`" which is the output of what's the uncommon value between both the arrays. Can some one help me out with the same! thanks!