public void checkIfExsists(int data)
 {
     if (headNode != null && headNode.data != data)
     {
         headNode.checkIfExsists(data);
     }
 }
 public void checkIfExsists(int data)
 {
     if (data == this.data)
     {
         Console.WriteLine("match at index {0}", counter);
         counter++;
     }
     else if (next != null && next.data != data)
     {
         next.checkIfExsists(data);
     }
 }