insert Nodes in the circular linked list
var head = null ; head = insertNode ( head , 1 ) ; head = insertNode ( head , 2 ) ; head = insertNode ( head , 3 ) ; head = insertNode ( head , 4 ) ; head = insertNode ( head , 5 ) ; head = insertNode ( head , 6 ) ; head = insertNode ( head , 7 ) ; head = insertNode ( head , 8 ) ; head = insertNode ( head , 9 ) ; var k = 4 ;