/**

  * Definition for ListNode.

  * public class ListNode {

  *     int val;

  *     ListNode next;

  *     ListNode(int val) {

  *         this.val = val;

  *         this.next = null;

  *     }

  * }

  */

 public class Solution {

     /*

      * @param head: The first node of linked list.

      * @param n: An integer

      * @return: Nth to last node of a singly linked list.

      */

     public ListNode nthToLast(ListNode head, int n) {

         // write your code here

         int number = 0;

         int count=0;

         ListNode p = head;

         while(p != null){

             number++;

             p = p.next;

         }

         p=head;

         while(count != (number-n)){

             count++;

             p=p.next;

         }

         return p;

     }

 }

  public class Solution {

      /**

       * @param head: The first node of linked list.

       * @param n: An integer.

       * @return: Nth to last node of a singly linked list.

       */

      ListNode nthToLast(ListNode head, int n) {

          // write your code here

          ListNode dummy = new ListNode(0);

          dummy.next = head;

          ListNode walker = dummy;

          ListNode runner = dummy;

          while (runner.next != null && n>0) {

              runner = runner.next;

              n--;

          }

          while (runner.next != null) {

              runner = runner.next;

              walker = walker.next;

          }

          return walker.next;

      }

  }