public int TreeHeigh(TreeNode root) {
		if(root == null) {
			return 0;
		}
		if(root.left == null && root.right == null) {
			return 1;
		}
		int leftHeigh = TreeHeigh(root.left);
		int rightHeigh = TreeHeigh(root.right);
		if(leftHeigh == -1 || rightHeigh == -1) {
			return -1;
		}
		if(Math.abs(leftHeigh-rightHeigh) > 1) {
			return -1;
		} else {
			if(leftHeigh > rightHeigh) {
				return (leftHeigh+1);
			}else {
				return (rightHeigh+1);
			}
		}
		
		
	}