The goal is to implement a basic singly linked list that can store integer values, support adding elements, retrieving and updating values by index, deleting elements, and returning the current size of the list. You will focus on handling nodes correctly and maintaining the count of elements.

1. In the size() method:
   • Return the current number of elements in the list.
2. In the delete(int index) method:
   • When checking bounds, the lower limit should be 0.
   • Use size() to check the upper limit.
   • If deleting the first element (index == 0), set head to the next node.
   • To delete a node at a non-zero index:
     • Start with a prev node pointing to head.
     • Use a loop to move prev to the node just before the one to delete.
     • Adjust the next reference to skip over the deleted node.
   • After deletion, decrement the count variable.