class Solution:

    def __init__(self):

        self.li = []

    def midSearch(self,node):

        if(node != None):

            self.midSearch(node.left)

            self.li.append(node.val)

            self.midSearch(node.right)

    def rangeSumBST(self, root, L, R):

        self.midSearch(root)

        count = 0

        tag = False

        for l in self.li:

            if l == L:

                tag = True

            if tag:

                count += l

            if l == R:

                tag = False

        return count