3 level matrix

Hello everybody,
I have a problem to finish my exercise, there are three lists (listA, listB, listC) and three cells (H1), (L1), (M1).
A B C
1 listA listB listC
2 40 40 40
3 45 45 60
4 50 40 30
5 50 50 70
6 50 50 120
7 60 40 30
8 60 40 40
If I select cell H1=60 (belong to listA) , L1=40 (belong to listB), M1 should be a dropdown list that returns two values:40 and 30 (belong to listC)
what i have to type on the Source of dropdown list?
thank you very much in advance

Thank you oeldere
in the excel file I have to associate a drop down list to cell (L2) "PickListC" once are selected the values in "PickListA" and "PickListB"
Thanks

Thank you oeldere
If you take a look to excel file and select the drop downlist in H2 and J2 you should obtain corrisponding values to ListA and ListB respectively, so I have to create a dropdown list in L2 that returns 1 or more values on the ListC.
Example:
if I choose for H2=60 and J2=40 L2= should return in dropdown list 30 and 40 (exactly how B7=60, C7=40, D7=30 D8=40)
Please accept my Apologize if i'm not so clear, my language is not English!!
thank you

Here's a vba solution.
Try the attached.

Hi PietBom
I appreciate a lot all the help you've given me,
thank you very much your file works great!!!
thanks

Hi Great Jindon
Your file is amazing and optimized
thank you very much for your help

Here's "Optimized" style of validation list. (all unique)

Try

Hi Oelder thank you for your file and your help
my language is not English!!
your English is much better than mine!!

I want express my vivid thanks for your quick support, guys!!!
thank you so much