Assume entries in a linked list are of type struct listrec: struct listrec value int struct listrec next; Write a main) routine in which you create the following linked list: 4 3NULL Write a function called listsize that takes a pointer to the start of a linked list and returns the number of elements in the list, and another function called listsum that also takes a pointer to the start of a linked list and returns the sum of the values of all elements in the computer screen