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def func(root):
    if root.left is None and root.right is None:
        return [str(root.value)]
    return [i + str(root.value) for i in func(root.left)] + [i + str(root.value) for i in func(root.right)]

def solve(root):
    paths = sum(int(i[::-1], 2) for i in func(root))
    return paths