my $after = [qw(2 3 4 1 5 6 7 8 9 10)];
for (my $i = 1; $i < scalar($after); $i++){
   my $diff = after->[$i-1] - $after->[$i];
   if($diff > 0){
      if($diff > $i){
         printf "$after->[$i-1] moved to position %d\n",($i-1);
      }
      else{
         print "$after->[$i] moved to position $i\n";
      }
      last;
   }
}