Thanks a lot FunkyMonk

I have tried your method.

However, I did not understand the line :$Hash{$k} += $v;
I replaced with line :$Hash{$v} = $k;
because I would like o have a unique list of the letters (not the numbers)

In reply to Re^2: suppress the elements that appear more than one time in a list by steph_bow
in thread suppress the elements that appear more than one time in a list by steph_bow

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