Add a value to a set. Do nothing if the given value already exists. The time complexity is O(log size).

Check whether a value belongs to a set. The time complexity is O(log size).

Create an empty set.

Iterate over elements in ascending order.

Check whether a set is empty.

Return the maximum element of a set. The time complexity is O(log size).

Return the minimum element of a set. The time complexity is O(log size).

Remove an element from a set. Do nothing if the given value does not exist. The time complexity is O(log size).

Create a set with a single element.

Return the number of key-value pairs. The time complexity is O(1).