Add and remove set elements

Summary

Practice adding and removing elements from a set and returning the final contents.

Problem statement

Implement a function that starts from an initial collection of items, adds items from a 'to_add' collection and removes items from a 'to_remove' collection. Use a set for these operations. Use discard when removing to avoid errors if an element is not present. Return the final unique items as a sorted list to keep output deterministic.

Task

Perform additions and removals on a set (using add and discard) and return a deterministic, sorted list of the final elements.

Examples

Input format

Three lists: initial, to_add, to_remove.

Output format

A sorted list with the final unique elements after additions and removals.

Constraints

All items are hashable and of comparable type for sorting. to_add and to_remove may contain duplicates.

Samples