Linq to XML get distinct

I am pretty new to LINQ and hence having difficuilty in writing Linq to xml query for foloowing xml

<?xml version="1.0" encoding="UTF-8" standalone="true"?>
-<LetterCode>
<Letter>A</Letter>
<Letter>A</Letter>
<Letter>B</Letter>
<Letter>B</Letter>
<Letter>C</Letter>
<Letter>C</Letter>
<Letter>C</Letter>
<Letter>C</Letter>
-<LetterCode>

I want to wrirte a linq query to get only distinct letters from this xml. Is this possible? I have tried some online resources by thi sxml structer seems different that those shown online

Thanks,

Kanchan