text: Driver program
code: public static void main ( String [ ] args ) { String tree = " ( 0(5(6 ( ) ( ) ) ( 4 ( ) (9 ( ) ( ) ) ) ) ( 7(1 ( ) ( ) ) ( 3 ( ) ( ) ) ) ) " ; int k = 2 ; System . out . println ( productAtKthLevel ( tree , k ) ) ; } }