net.sf.jsqlparser.parser.ParseException: Encountered unexpected token: "+" "+"
 at line 1, column 155. Was expecting one of: ")"

SELECT (
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 INNER JOIN ORDER O ON O.CUSTOMER_ID = C.CUSTOMER_ID
 INNER JOIN PAYMENT P ON P.ORDER_ID = O.ORDER_ID
 )
 +
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 INNER JOIN ADDRESS A ON A.CUSTOMER_ID = C.CUSTOMER_ID
 INNER JOIN CITY CT ON CT.CITY_ID = A.CITY_ID
 )
) AS TOTAL_ASSOC;

SELECT (
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 )
 +
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 )
) AS TOTAL_ASSOC;

SELECT
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 INNER JOIN ORDER O ON O.CUSTOMER_ID = C.CUSTOMER_ID
 INNER JOIN PAYMENT P ON P.ORDER_ID = O.ORDER_ID
 )
 +
 (SELECT COUNT(1) 
 FROM CUSTOMER C
 INNER JOIN ADDRESS A ON A.CUSTOMER_ID = C.CUSTOMER_ID
 INNER JOIN CITY CT ON CT.CITY_ID = A.CITY_ID
 ) AS TOTAL_ASSOC;