Matching four lists of numbers

There are four columns of numbers. I would like to have a formula that will look at the numbers in column A and find matches in columns B, C and D. If there is a match in A, then return the text "A", if the match is in B, return "B", if in D, return "D" if no match, then return nothing (or "0").
Anyone have a good way to do this? My attempts failed.
Many thanks.

Sorry...The numbers in cols B,C and D are never duplicates. Also, the numbers are never more than 4 digits.

Thanks, but I can't make your suggestion work
More info. The matching numbers in columns B,C,D in my original question could be anywhere in the list.
Example
A B C D E
Value List A List B List C Formula Results
1 1 10 3 B
2 8 9 12 C
3 7 2 13 D
4 6 11 4 D
Any ideas?

Heck, my column spacing got taken away with the previous post.
Here is a file

Input formula in cell E3 and copy down.

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Hope it helps!

Thanks to everyone.
Vane, I think I'll use your one column formula. Whew!
Many, many thanks to all.