if (
   #Brian next to Dana
   abs($positions{Brian} - $positions{Dana}) == 1
   #Dana not next to Evan
   && abs($positions{Dana} - $positions{Evan}) > 1
   #Carlos on Dana's right
   && $positions{Carlos} - $positions{Dana} == 1
   #one seat between Brian and Farra
   && abs($positions{Brian} - $positions{Farra}) == 2;
) {
   print "@perm\n";
 }