Use push ( ) to construct linked list
head = push ( head , 1 ) ; head = push ( head , 2 ) ; head = push ( head , 1 ) ; head = push ( head , 12 ) ; head = push ( head , 1 ) ; head = push ( head , 18 ) ; head = push ( head , 47 ) ; head = push ( head , 16 ) ; head = push ( head , 12 ) ; head = push ( head , 14 ) ;