Linkedlist cycle-II

/****************************************************************

 Following is the class structure of the Node class:

 class Node {
     public int data;
     public Node next;

     Node()
     {
         this.data = 0;
         this.next = null;
     }
     Node(int data)
     {
         this.data = data;
         this.next = null;
     }
     Node(int data, Node next)
     {
         this.data = data;
         this.next = next;
     }
 }

 *****************************************************************/

public class Solution {
    public static Node firstNode(Node head) {
        Node fast=head;
        Node slow=head;
        Node ans=head;
        while(fast!=null  && fast.next!=null)
        {
                   slow=slow.next;
            fast=fast.next.next;
     
            if(slow==fast){
                while(ans!=slow)
                {
                    ans=ans.next;
                    slow=slow.next;
                }
                return ans;                        

            }
          
            
        }return null;
    }
}