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class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if (root == null) return null;

        if (root == p || root == q) return root;

        TreeNode left = lowestCommonAncestor(root.left, p, q);

        TreeNode right = lowestCommonAncestor(root.right, p, q);



        if (left != null && right != null) return root;

        else if (left != null) return left;

        else return right;
    }
}