diff --git a/HW1.fedorind.hs b/HW1.fedorind.hs
index 0cc2240..883ebee 100644
--- a/HW1.fedorind.hs
+++ b/HW1.fedorind.hs
@@ -191,7 +191,10 @@ inorder = treeFoldr (:) []
 --   True
 --
 isBST :: Tree -> Bool
-isBST tree = snd $ treeFoldl (\v (p, b) -> (v, b && v >= p)) (minInt tree, True) tree
+isBST tree = snd $ treeFoldl accCompare (firstNum, True) tree
+    where
+        accCompare v (p, b) = (v, b && v >= p)
+        firstNum = leftmost tree
 
 -- | Check whether a number is contained in a binary search tree.
 --   (You may assume that the given tree is a binary search tree.)