public boolean isSameTree(TreeNode p, TreeNode q) {
		// Start typing your Java solution below
		// DO NOT write main() function
		if (p == null && q == null)
			return true;
		if (p == null || q == null)
			return false;
		if (p.val == q.val && isSameTree(p.left, q.left)
				&& isSameTree(p.right, q.right))
			return true;
		return false;
	}