How to display multiple cell values ​​by condition in Excel?

Question

excel

There is a table with a list of products. It indicates which warehouse this product is in.

At the moment, the formula =JOIN(",";;IF($B$1:$G$1=A9;$A$2:$A$6;"")) displays all products, but you want to display only those where worth "+".
I think that it is possible to add the CELL function, but I do not know where and how to substitute it in the expression.