diff --git a/exercises/Set3a.hs b/exercises/Set3a.hs
index c63f194..408e094 100644
--- a/exercises/Set3a.hs
+++ b/exercises/Set3a.hs
@@ -218,6 +218,11 @@ allCombinations xs = merge (map (`allCombinationsWithStr` xs) xs) []
 --   [1,2,3] +|+ [4,5,6]  ==> [1,4]
 --   [] +|+ [True]        ==> [True]
 --   [] +|+ []            ==> []
+(+|+) :: [a] -> [a] -> [a]
+[] +|+ [] = []
+a +|+ [] = [head a]
+[] +|+ b = [head b]
+a +|+ b = [head a, head b]
 
 
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